[Federal Register Volume 70, Number 193 (Thursday, October 6, 2005)]
[Proposed Rules]
[Pages 58508-58561]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-19419]
[[Page 58507]]
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Part II
Department of Transportation
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Federal Aviation Administration
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14 CFR Parts 1, 25, 91, etc.
Enhanced Airworthiness Program for Airplane Systems/Fuel Tank Safety
(EAPAS/FTS); Proposed Advisory Circulars; Proposed Rule and Notices
Federal Register / Vol. 70, No. 193 / Thursday, October 6, 2005 /
Proposed Rules
[[Page 58508]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Parts 1, 25, 91, 121, 125, 129
[Docket No. FAA-2004-18379; Notice No. 05-08 ]
RIN 2120-AI31
Enhanced Airworthiness Program for Airplane Systems/Fuel Tank
Safety (EAPAS/FTS)
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The intent of this proposal is to help ensure the continued
safety of commercial airplanes by improving the design, installation,
and maintenance of their electrical wiring systems as well as by
aligning those requirements as closely as possible with the
requirements for fuel tank system safety. This proposed rulemaking
consists of regulatory changes affecting wiring systems and fuel tank
systems in transport category airplanes. First, it proposes to organize
and clarify design requirements for wire systems by moving existing
regulatory references to wiring into a single section of the
regulations specifically for wiring and adding new certification rules.
It also proposes to require holders of type certificates for certain
transport category airplanes to conduct analyses of their airplanes and
make necessary changes to existing Instructions for Continued
Airworthiness (ICA) to improve maintenance procedures for wire systems.
It would require operators to incorporate those ICA for wiring into
their maintenance or inspection programs. And finally, this proposed
rulemaking would clarify requirements of certain existing rules for
operators to incorporate ICA for fuel tank systems into their
maintenance or inspection programs.
DATES: Send your comments on or before February 3, 2006.
ADDRESSES: You may send comments [identified by Docket Number FAA-2004-
18379] using any of the following methods:
DOT Docket Web site: Go to http://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your
comments electronically.
Mail: Docket Management Facility; U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401,
Washington, DC 20590-001.
Fax: 1-202-493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For more information on the rulemaking process, see the
SUPPLEMENTARY INFORMATION section of this document.
Privacy: We will post all comments we receive, without change, to
http://dms.dot.gov, including any personal information you provide. For
more information, see the Privacy Act discussion in the SUPPLEMENTARY
INFORMATION section of this document.
Docket: To read background documents or comments received, go to
http://dms.dot.gov at any time or to Room PL-401 on the plaza level of
the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
FOR FURTHER INFORMATION CONTACT: Stephen Slotte, ANM-111, Airplane &
Flight Crew Interface, Federal Aviation Administration, 1601 Lind
Avenue SW., Renton, WA 98055-4056; telephone (425) 227-2315; facsimile
(425) 227-1320, e-mail [email protected] (certification rules) or
Fred Sobeck, AFS-304, Aircraft Maintenance Division, Federal Aviation
Administration, 800 Independence Avenue, SW., Washington, DC 20591;
telephone: (202) 267-7355; facsimile (202) 267-7335, e-mail
[email protected] (operating rules).
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. We also
invite comments relating to the economic, environmental, energy, or
federalism impacts that might result from adopting the proposals in
this document. The most helpful comments reference a specific portion
of the proposal, explain the reason for any recommended change, and
include supporting data. We ask that you send us two copies of written
comments.
We will file in the docket all comments we receive, as well as a
report summarizing each substantive public contact with FAA personnel
about this proposed rulemaking. The docket is available for public
inspection before and after the comment closing date. If you wish to
review the docket in person, go to the address in the ADDRESSES section
of this preamble between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. You may also review the docket using the
Internet at the Web address in the ADDRESSES section.
Privacy Act: Using the search function of our docket Web site,
anyone can find and read the comments received into any of our dockets,
including the name of the individual sending the comment (or signing
the comment on behalf of an association, business, labor union, etc.).
You may review DOT's complete Privacy Act Statement in the Federal
Register published on April 11, 2000 (65 FR 19477-78) or you may visit
http://dms.dot.gov.
Before acting on this proposal, we will consider all comments we
receive on or before the closing date for comments. We will consider
comments filed late if it is possible to do so without incurring
expense or delay. We may change this proposal in light of the comments
we receive.
If you want the FAA to acknowledge receipt of your comments on this
proposal, include with your comments a pre-addressed, stamped postcard
on which the docket number appears. We will stamp the date on the
postcard and mail it to you.
Availability of Rulemaking Documents
You can get an electronic copy using the Internet by:
(1) Searching the Department of Transportation's electronic Docket
Management System (DMS) Web page (http://dms.dot.gov/search);
(2) Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies/; or
(3) Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.html.
You can also get a copy by submitting a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make
sure to identify the docket number, notice number, or amendment number
of this rulemaking.
Organization of This NPRM
Discussion of the proposal in this NPRM is organized under the
following headings. Material supplementary to this discussion, but not
included in it, appears in appendices at the end of the discussion,
before ``List of Subjects.'' Whenever there is a reference to a
document being included in the docket
[[Page 58509]]
for this NPRM, the docket referred to is Docket Number FAA-2004-18379.
A list of acronyms used is included as Appendix A. Unless stated
otherwise, rule sections referenced in this NPRM are part of Title 14
of the Code of Federal Regulations.
Table of Contents
I. Executive Summary
II. Background
A. Flight 800 Accident
B. Flight 111 Accident
C. FAA Aging Transport Nonstructural Systems Plan
D. Fuel Tank Safety Rule
E. Existing Wiring Certification Regulations
III. General Discussion of the Proposal
A. Nature of the Problem
B. Relationship of this Proposal to Other Aging Aircraft
Initiatives
C. Alternatives to Rulemaking
IV. Overview of Proposal
V. Section-by-Section Discussion of Proposed Rules
A. Part 25 Subpart H-Electrical Wiring Interconnection Systems
(EWIS)
B. Part 25 Subpart I--Continued Airworthiness and Related Part
25 Changes
C. Other Proposed Changes to Part 25
D. Part 25 Electrical System Harmonization Rules
E. Proposed Changes to Part 91, 121, 125, and 129 Operating
Rules for Fuel Tank Systems and EWIS and Other Existing Continued-
Airworthiness-Related Rules
F. Proposed Changes to Parts 121 (Subpart Y) and 129 (Subpart
B)-EWIS Maintenance Programs
G. Proposed Changes to Parts 91 (Subpart L), 121 (Subpart Y),
125 (Subpart M), and 129 (Subpart B) ( Fuel Tank Maintenance
Programs
H. Advisory Circulars
VI. Regulatory Analyses and Notices
Appendices
Appendix A--List of Acronyms
Appendix B--Correlation Between Proposed New Part 25 Regulations
and Existing Regulations
Appendix C--Correlation Between Existing Part 25 Regulations and
Proposed New Regulations
Appendix D--Existing Part 25 Requirements Requiring Revision to
Support the New Proposed Regulations
Appendix E--Flowchart 1: Pre- and Post-Type Certification Safety
Analysis Concept--Flowchart 2: Post-TC Safety Analysis Concept
I. Executive Summary
Safety concerns about wiring systems in airplanes were brought to
the forefront of public and governmental attention by a mid-air
explosion in 1996 involving a 747 airplane. Ignition of flammable
vapors in the fuel tank was the probable cause of that fatal accident
and the most likely source was determined to be a wiring failure
causing a spark to enter the fuel tank. All 230 people aboard were
killed. Two years later, an MD-11 airplane crashed into the Atlantic
Ocean, killing all 229 people aboard. Although an exact cause could not
be determined, a region of resolidified copper on a wire of the in-
flight-entertainment system cable indicated that wire arcing had
occurred in the area where the fire most likely originated.
Investigations of those accidents and subsequent examinations of
other airplanes showed that deteriorated wiring, corrosion, improper
wire installation and repairs, and contamination of wire bundles with
metal shavings, dust, and fluids, which would provide fuel for fire,
were common conditions in representative examples of the ``aging fleet
of transport airplanes.'' The FAA concluded that current maintenance
practices do not adequately address wiring components, wiring
inspection criteria are too general, and unacceptable conditions, such
as improper repairs and installations, are not described in enough
detail in maintenance instructions. Wiring failures result in airplane
delays, unscheduled landings, in-flight entertainment system problems,
nonfatal accidents, and fatal accidents.
Up until this time, airplane wiring has never been singled out for
special attention during maintenance inspections. Although close
attention is paid to safe design within systems, we had assumed that
for the wiring providing power to those systems, standard industry
practice was appropriate, and modifications have often been performed
without scrutiny for the effect their wiring additions may have on
other systems in the airplane. Damaged wire and insulation can cause
electrical arcing, providing the spark that can cause fire. Dust, dirt,
lint, contamination, and vapors provide fuel for fire. Recent rules
have established requirements for wiring connected to fuel tank
systems. This proposal goes further, to address all the wiring
contained in an airplane as systems on their own and provide scrutiny
to the conditions that affect their safe functioning. It aligns with
the requirements for fuel tank wiring.
We are proposing new maintenance, inspection, and design criteria
for airplane wiring to address conditions that put transport airplanes
at risk of wire failures, smoke, and fire. We are proposing
requirements for type certificate holders and applicants for type
certificates and supplemental type certificates to analyze all the
zones of their airplanes for the presence of wire and for the
likelihood of contaminant materials. The proposal would also require
them to develop maintenance and inspection tasks to identify, correct,
and prevent wiring conditions that cause risk to continued safe flight.
We are proposing that these tasks be included in new instructions for
continued airworthiness for wiring and that they be compatible with
instructions for continued airworthiness for fuel tank systems. We are
further proposing to amend Title 14 Code of Federal Regulations (CFR)
parts 91, 121, 125 and 129 operating rules to require operators of
transport airplanes to incorporate those tasks for wiring and fuel
tanks into their regular maintenance programs. Finally, we are creating
a new subpart of part 25 to contain all applicable certification
requirements for airplane wiring, including new rules to improve safety
in manufacture and modification.
The total estimated benefits of the proposal are comprised of
efficiency benefits and safety benefits. The efficiency benefits are
$192.3 million ($78.3 million present value). The safety benefits are
$563 million ($262.4 million present value). From 1995-2002, 397 wiring
failures were reported. We used industry estimates to determine that
68% of those failures would be detectable. The 7 most common--burned,
loose, damaged, shorted, failed, chafed, and broken wires--account for
84% of all wiring failures. Wiring failures cause 22.1 flight delays
per year, with an average time of 3.5 hours and an estimated cost of
approximately $35,639 each, and without this proposal, we believe that
wiring delays will increase proportionately with the growth of the
fleet. Wiring failures cause 27.5 unscheduled landings per year at an
average cost of approximately $200,461 per unscheduled landing. We
estimate that, based on expected fleet growth of 3.82% per year, there
will be 1,118 unscheduled landings caused by wiring failures over a 25-
year period, of which approximately 760 would be prevented by this
proposal, resulting in a total benefit of averting unscheduled landings
of $152.4 million. Delays and unscheduled landings contain safety risks
for passengers and crew and increase the likelihood of a more serious
event. We estimate 32.8 wiring-related incidents or accidents could be
prevented by this proposal in the next 25 years, for a total safety
benefit of $563 million ($262.4 million present value). This includes
1.2 fatal accidents that can be prevented.
The estimated total cost of this NPRM is $474.4 million ($209.2
million present value) over 25 years. The total estimated benefits are
$755.3 million
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($340.7 million present value) over the same period. This proposal is
meant to proactively address wiring conditions existing in the
transport airplane fleet that we now know affect safe flight and can be
detected, corrected, or prevented.
II. Background
A. Flight 800 Accident
Safety concerns about wiring systems in airplanes were brought to
the forefront of public and governmental attention by a 1996 accident
over the Atlantic Ocean near East Moriches, New York, involving a 747-
131 airplane, operated as TWA Flight 800. That accident was
investigated extensively by the National Transportation Safety Board
(NTSB). It also prompted the FAA to investigate fuel tank wiring, and
to focus on aging wiring in general. On May 7, 2001, the FAA published
a final rule titled ``Transport Airplane Fuel Tank System Design
Review, Flammability Reduction, and Maintenance and Inspection
Requirements'' (66 FR 23086) to specifically address safety of the fuel
tank, including wiring, which was determined to be the probable cause
of the TWA Flight 800 accident. This NPRM addresses safety concerns
related to aging wiring in general, and incorporates maintenance
requirements specific to fuel tanks.
The NTSB determined the probable cause of the TWA Flight 800
accident, in which the airplane broke up in flight, was an explosion of
the center wing fuel tank (CWT) resulting from ignition of the
flammable fuel and air mixture in the tank. The source of ignition
energy for the explosion could not be determined with certainty.
However, of all the sources evaluated, the most likely was a wiring
failure outside the CWT. This failure allowed excessive electrical
energy to enter the CWT through electrical wiring associated with the
fuel quantity indication system (FQIS).
During its investigation, the NTSB found several potentially unsafe
conditions in and near the electrical wiring of the accident airplane.
The findings included cracked wire insulation, metal shavings adhered
to a floor beam where FQIS wires would have been routed (consistent
with maintenance records describing compressed air being used to blow
metal shavings off avionics units), other debris, and sulfide deposits.
In addition, it found evidence of several repairs that did not comply
with the guidelines in Boeing's ``Standard Wiring Practices Manual''
(SWPM). Noncompliant repairs included:
Use of an oversized strain relief clamp on the terminal
block of the number 1 fuel tank compensator. The clamp did not
adequately secure the wires.
Many open-ended (rather than sealed) wire splices, which
exposed conductors to possible water contamination.
Several wire bundles containing many wire splices on
adjacent wires at the same location.
Excessive solder on the connector pins inside the fuel
totalizer gauge. The solder had apparently caused inadvertent joining
of connecting pins/wires from the right main fuel tank and CWT FQIS.
Some of these conditions may suggest the need for improved
maintenance. However, the NTSB found that deterioration, damage, and
contamination of aircraft wiring and related components, such as those
found on the accident airplane, were common in other transport category
airplanes inspected as part of the accident investigation. This was
especially true in older airplanes. The NTSB concluded that ``the
condition of the wiring system in the accident airplane was not
atypical for an airplane of its age and one that had been maintained in
accordance with prevailing industry practices.''
The NTSB expressed concern about the damage and contamination found
on electrical wiring and components during their examinations of
numerous transport category airplanes, including the accident airplane.
The conditions found were especially disturbing because it was clear
from those examinations that much aircraft wiring is difficult, if not
impossible, to inspect and test because of its inaccessibility.
The NTSB concluded that inadequate attention to the condition of
aircraft electrical wiring had resulted in potential safety hazards.
The conclusions from the accident investigation brought a heightened
awareness to the FAA, other government agencies, and the general public
of the importance of maintaining the integrity of aircraft wiring. A
copy of the NTSB findings (NTSB Aircraft Accident Report Number AAR-00/
03) can be found on the NTSB Web site http://www.NTSB.gov, and is
contained in the docket.
B. Flight 111 Accident
Two years after the Flight 800 accident, in September 1998, an MD-
11 airplane, operated as Swissair Flight 111, crashed into the Atlantic
Ocean off the coast of Nova Scotia, Canada. There were no survivors.
Within approximately 53 minutes of the airplane's departure from New
York to Geneva, Switzerland, the flightcrew smelled an abnormal odor in
the cockpit. The cockpit voice recorder indicates that they thought the
smell was coming from the air-conditioning system. A short time after
the flightcrew noticed the smell, there was smoke in the cockpit, and
they diverted the airplane to the Halifax airport.
While preparing for landing, the flightcrew were unaware that fire
was spreading above the ceiling in the front of the aircraft. They
declared an emergency and signaled a need to land immediately. About
one minute later, radio communications and secondary radar contact with
the aircraft were lost, and the flight recorders stopped functioning.
About five and one-half minutes later, the aircraft crashed into the
ocean.
In its final report, ``Aviation Investigation Report, In-Flight
Fire Leading to Collision with Water,'' Report Number A98H0003, the
Transportation Safety Board of Canada (TSB) (the Canadian governmental
body charged with aircraft accident investigation) could not identify
the exact cause of the fire. As part of its 11 findings of causes and
contributing factors, however, the TSB stated that: ``A segment of in-
flight entertainment network power supply unit cable exhibited a region
of resolidified copper on one wire that was caused by an arcing event.
This resolidified copper was determined to be located in the area where
the fire most likely originated. This arc was likely associated with
fire initiation event; however, it could not be determined whether this
arced wire was the lead event.'' That report can be found in the
docket.
In the section of the report entitled ``Findings as to Risk,'' the
TSB cited 24 separate risks that had the potential to degrade aviation
safety but could not be shown to have played a direct role in the
event, or are unrelated to this event but were found during the
investigation. Among those findings of risks are the following
statements. (The numbers under which each finding appears in the TSB
report are indicated.)
``Regulations do not require that aircraft be designed to
allow for the immediate de-powering of all but the minimum essential
electrical systems as part of an isolation process for the purpose of
eliminating potential ignition sources.'' (3.2.3)
``Examination of several MD-11 aircraft revealed various
wiring discrepancies that had the potential to result in wire arcing.
Other agencies have found similar discrepancies in
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other aircraft types. Such discrepancies reflect a shortfall within the
aviation industry in wire installation, maintenance, and inspection
procedures.'' (3.2.7)
``The consequence of contamination of an aircraft on its
continuing airworthiness is not fully understood by the aviation
industry. Various types of contamination may damage wire insulation,
alter the flammability properties of materials, or provide fuel to
spread a fire. The aviation industry has yet to quantify the impact of
contamination on the continuing airworthiness and safe operation of an
aircraft.'' (3.2.8)
``There is no guidance material to identify how to comply
with the requirements of Federal Aviation Regulation (FAR) 25.1353(b)
[relating to cable routing] in situations where physical/spatial wire
separation is not practicable or workable, such as in confined areas.''
(3.2.10)
``Inconsistencies with respect to CB (circuit breaker)
reset practices have been recognized and addressed by major aircraft
manufacturers and others in the aviation industry. Despite these
initiatives, the regulatory environment, including regulations and
advisory material, remains unchanged, creating the possibility that
such ``best practices'' will erode or not be universally applied across
the aviation industry.'' (3.2.12)
``FAR 25.1309 requires that a system safety analysis be
accomplished on every system installed in an aircraft; however, the
requirements of FAR 25.1309 are not sufficiently stringent to ensure
that all systems, regardless of their intended use, are integrated into
the aircraft in a manner compliant with the aircraft's type
certificate.'' (3.2.21)
In addition to the two accidents discussed above, multiple
incidents and accidents that have occurred over the years illustrate
the types of wire malfunctions that can affect flight safety. A
discussion of some of those, titled ``EAPAS NPRM Supplemental Material,
Other Incidents and Accidents Involving Electrical Wiring,'' is
included in the docket for this NPRM.
C. FAA Aging Transport Nonstructural Systems Plan
After the Flight 800 accident, at the recommendation of the White
House Commission on Aviation Safety and Security (WHCSS), the FAA
expanded its Aging Aircraft Program, which in the past had focused on
structures, to cover nonstructural systems. We formed a team to study
aging nonstructural systems and conduct detailed physical evaluations
of aging airplanes. We reviewed the report from that study team, along
with information from meetings with FAA principal inspectors and
representatives of major airplane manufacturers, as well as an analysis
of airplane service histories. From this combined information, we
developed the Aging Transport Nonstructural Systems Plan (included in
the docket for this NPRM). The plan's primary focus is on electrical
wiring systems. There are other on-going research and development
activities that address mechanical and avionics systems.
The July 1998 Aging Transport Nonstructural Systems Plan includes
results of the evaluation of five transport category airplanes
considered representative of the ``aging fleet of transport
airplanes.'' The FAA found conditions similar to those the NTSB found
during its investigation of the TWA Flight 800 accident. Those
conditions included:
Deterioration of wiring and related components.
Stiff and cracked wire.
Contamination of wire bundles with metal shavings, dust,
and fluids.
Corrosion on connector pins.
Improper wire installation and repairs.
The FAA also found, as had NTSB investigators, that wires contained
in wire bundles are difficult to inspect.
The conclusions reached from this evaluation were that:
Current maintenance practices do not adequately address
wiring components.
Wire inspection criteria are too general.
Unacceptable conditions, such as improper repairs and
installations, are not described in enough detail in maintenance
instructions.
Repair instructions and data are difficult to extract from
SWPMs.
The information that maintenance personnel are given for
wire replacement may not be adequate.
Current incident/maintenance reporting procedures do not
allow for easy identification of failures.
The NTSB agreed with these conclusions.
The Aging Transport Nonstructural Systems Plan detailed several
tasks and associated subtasks aimed at correcting these problems,
including:
Improving wiring inspection criteria and providing more
detailed descriptions of undesirable conditions.
Improving inspector training to ensure that it adequately
addresses the recognition and repair of aging wiring components.
Developing new methods for nondestructive testing of
wiring.
The NTSB responded to the issues defined in the Aging Transport
Nonstructural Systems Plan. They concluded that they are important
safety issues and must be fully addressed through rulemaking or other
means. Specifically addressed by the NTSB (NTSB Recommendation No. A-
00-108, included in the docket) were the need for:
Improved training of maintenance personnel to ensure
adequate recognition and repair of potentially unsafe wiring
conditions;
Improved documentation and reporting of potentially unsafe
electrical wiring conditions; \1\ and
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\1\ Recommendations for improved documentation and reporting and
for incorporation of new technology are not addressed by this
proposed rule. They are, however, part of the FAA's Enhanced
Airworthiness Program for Airplane Systems (EAPAS). The EAPAS
report, dated October 15, 2002, can be found in the docket for this
NPRM. For a discussion of training, see ``ATSRAC Recommendations for
Rulemaking'' in the same docket.
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Incorporation of the use of new technology, such as arc-
fault circuit breakers and automated wire test equipment.
The NTSB also recommended (NTSB Recommendation A-00-106, included
in the docket) that the FAA review the design specifications for
aircraft wiring systems of all U.S.-certified aircraft and then:
Identify which systems are critical to safety; and
Require revisions, as necessary, to ensure that adequate
separation is provided for the wiring related to those critical
systems.
Finally, the NTSB recommended that the FAA ensure that all part 25
transport category airplanes, regardless of whether they are operated
under parts 91, 121, 125, or 135, be included in the review of aging
transport airplane systems and structures (NTSB Recommendation A-00-
119, contained in the docket).
The FAA Administrator established a formal advisory committee (the
Aging Transport Systems Rulemaking Advisory Committee, or ATSRAC) in
1998. Its purpose was to facilitate actions recommended by the Aging
Transport Nonstructural Systems Plan (FAA Order 11110.127, Aging
Transport Systems Rulemaking Advisory Committee, dated Jan. 19, 1999,
included in the docket). This committee is made up of representatives
of aircraft manufacturers, transport airplane operators, aerospace and
industry associations, and governmental agencies.
In January 1998, the FAA assigned five tasks to ATSRAC. These
included collecting data on aging wiring systems through airplane
inspections, reviewing
[[Page 58512]]
airplane manufacturers' service information, reviewing operators'
maintenance programs, and providing the FAA with recommendations to
improve the safety of those systems. ATSRAC's work on those tasks
focused on transport category airplanes.
The ATSRAC review of data (The ``Aging Systems Task Force Aging
Transport Systems Task 1 and Task 2 Final Report,'' included in the
docket) yielded the following wiring-related findings:
Nine B-727 airplanes inspected; 276 discrepancies found.
Nine B-737 airplanes inspected; 399 discrepancies found.
Seven B-747 airplanes inspected; 238 discrepancies found.
Fourteen DC-8 airplanes inspected; 974 discrepancies
found.
Fifteen DC-9 airplanes inspected; 116 discrepancies found.
Fourteen DC-10 airplanes inspected; 714 discrepancies
found.
Three L-1011 airplanes inspected; 247 discrepancies found.
Ten A-300 airplanes inspected; 408 discrepancies found.
The results from those five initial tasks showed that problems
related to wiring systems on aging airplanes were not entirely related
to degradation over time. Inadequate installation and maintenance
practices were identified as factors that can lead to what is commonly
referred to as an ``aging system'' problem. As a result, the scope of
ATSRAC's work was expanded to include improving the continued
airworthiness of airplane systems, particularly wiring systems.
In May 2001, the FAA assigned four new tasks to the committee to
carry out the ATSRAC recommendations on the first five tasks (66 FR
29203). These next tasks were to accomplish the following:
Address the need for new wire system certification
requirements.
Propose changes to the standard wiring practices manual.
Develop a training program for wire systems.
Develop maintenance criteria for wire systems.
The results discussed earlier from ATSRAC's review of the eight
models of large transport category airplanes had heightened concern
about whether similar conditions existed in small transport category
airplanes (airplanes with a 6- to 30-passenger seating capacity). As a
result, in March 2002 (67 FR 9799), the FAA assigned another task to
ATSRAC--to investigate and develop recommendations to improve the
safety of electrical wiring systems in transport category airplanes
certificated for fewer than 30 passengers. In response to this task,
ATSRAC examined the applicability of their previous recommendations to
this group of airplanes and identified issues unique to electrical
wiring systems on small transport category airplanes. ATSRAC's work in
this area is continuing.
Another investigative group functioning within ATSRAC, whose wiring
inspections extended to the laboratory, was the Intrusive Inspection
Working Group (IIWG).\2\ The IIWG subjected selected wire installations
on six decommissioned airplanes to an intensive, detailed visual
inspection, followed by destructive testing and laboratory analysis (an
intrusive inspection). They studied the results to assess the state of
wire on aged airplanes as a function of wire type and service history.
In addition, the results from the visual inspections were compared with
the nondestructive testing and laboratory analysis to determine the
efficacy of visual inspections for the detection of age-related
deterioration.
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\2\ The IIWG was a separate but parallel group within the Aging
Systems Task Force (ASTF). The Air Transport Association (ATA)
formed the ASTF in June 1998 to review the effectiveness of
maintenance on electrical wiring systems and assess the condition of
those systems on aircraft with type certificates (TC) older than 20
years. When ATSRAC was formed in 1998, it continued the work started
under the ASTF.
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The findings from the IIWG were documented in the ``Transport
Aircraft Intrusive Inspection Project (An Analysis of the Wire
Installations of Six Decommissioned Aircraft) Final Report,'' issued on
December 29, 2000 (from now on referred to as ``Intrusive Inspection
Report''). A copy is included in the docket. The findings showed that
wire-related failures have multiple causes. These include:
Localized heat damage.
Breaches in wire insulation.
Wire embrittlement.
Charred wire insulation.
Missing insulation.
Chafing.
Arcing.
Arc tracking.
Reduced insulation resistance in certain wires.
Defective and broken connectors.
Damage to connector backshells.
Both the nonintrusive, visual inspections on the airplane and the
intrusive inspections found most wiring discrepancies were in areas of
frequent maintenance activity. In addition, fluid contamination and
dust and dirt accumulations were common in those areas.
The Intrusive Inspection Report identified several areas that
required special emphasis. Three areas--the cockpit, electrical power
centers, and power feeder cables--were considered critical. This is
because chafing on wiring in these areas, combined with flammable
materials close by, can result in severe outcomes, such as wire-to-
structure or wire-to-wire shorting and arcing. Since a fire in these
areas could present a high risk to continued safe flight and landing,
the IIWG recommended more detailed inspections for those three areas.
The intent was to ensure potential problems are identified and
corrected. This effort led to the development of an enhanced zonal
analysis procedure (EZAP) to assess risk for fire so that maintenance
programs developed for wire systems in such critical areas would
require more detailed inspections. An EZAP is a specific wire-focused
version of the zonal analysis procedure widely used to analyze an
airplane's physical areas or zones. It's used for developing
maintenance tasks. One version of an EZAP is described in proposed AC
120-XX, ``Program to Enhance Transport Category Airplane Electrical
Wiring Interconnection System Maintenance.''
ATSRAC made a number of recommendations to the FAA. Those
recommendations and the FAA's responses to them are included in the
docket in the document titled ``ATSRAC Recommendations for
Rulemaking.'' ATSRAC working groups also produced four proposed
advisory circulars (AC) as guidance for their recommended rulemaking.
These proposed ACs are on the topics of wiring system maintenance,
training, standard wiring practices manuals, and the proposed subpart
H, and will be briefly discussed at the end of this preamble under the
heading ``Advisory Circulars.''
D. Fuel Tank Safety Rule
In addition to the activities described earlier, in response to the
TWA 800 accident, the FAA has developed an extensive program to address
safety problems associated specifically with fuel tanks. As mentioned
previously, on May 7, 2001, the FAA issued a final rule entitled,
``Transport Airplane Fuel Tank System Design Review, Flammability
Reduction, and Maintenance and Inspection Requirements.'' This
discussion refers to that final rule as the ``Fuel Tank Safety Rule.''
The Fuel Tank Safety Rule was issued to address unforeseen failure
modes and the lack of specific maintenance procedures that could result
in degrading the design safety features intended to preclude ignition
of fuel tank vapors.
One part of the Fuel Tank Safety Rule, Special Federal Aviation
Regulation 88,
[[Page 58513]]
(SFAR 88) applies to design approval holders of certain turbine-powered
transport category airplanes, and any person who modifies those
airplanes later. SFAR 88 requires these regulated parties to perform
safety assessments to confirm if the design of the fuel tank system
precludes the existence of ignition sources in the fuel tank system.
SFAR 88 also requires development of design changes and maintenance and
inspection instructions to assure the safety of the fuel tank system.
Other sections of the Fuel Tank Safety Rule (referred to as the
``operational rules'') require that operators of those airplanes
include fuel tank safety maintenance and inspection instructions in
their existing maintenance or inspection programs. The requirements of
those sections address two areas:
(i) The fuel tank systems of the ``baseline'' airplane (as
originally made by the TC holder); and
(ii) The ``actual configuration'' of the fuel tank systems of each
affected airplane (as modified or altered after original manufacture).
As discussed later, one purpose of this rulemaking is to make sure
that the implementation of this proposal for wiring is aligned with the
implementation of the Fuel Tank Safety Rule.
E. Existing Wiring Certification Regulations
Traditionally, wire has not been looked upon as having the same
importance to safety as the rest of the systems for which it provides
the electrical interconnection. Whereas a particular piece of
electrical equipment may be the focus of intense scrutiny regarding its
design, installation, and maintenance, the wires that provide the
electrical interconnection to that equipment have not received the same
amount of attention, except for the wiring on engines. Additionally, in
the past, system safety assessments usually addressed only the effect
of a wire failure on the system itself. The safety assessments have not
usually identified the effect of wire failures on other systems or on
the airplane.
Existing regulations fall short of providing specific wiring-
related requirements that we now recognize should be included. For
example, current rules do not adequately address requirements for wires
in system separation, safety assessments, component selection,
component identification, protection in cargo and baggage compartments,
and accessibility for inspection, maintenance, and repair.
This quote from FAA Wiring Policy ANM-01-04 supports the need for
more specific wiring information: ``The FAA expects the applicant to
provide engineering drawings instead of merely statements such as
`install in accordance with industry standard practices,' or `install
in accordance with AC 43.13 [``Acceptable Methods, Techniques, and
Practices--Aircraft Inspection and Repair''].' The FAA considers such
statements inadequate because the standard practices cannot define the
location or routing of the wiring to the level needed to ensure that
new/modified wiring does not invalidate previous certification findings
for existing airplane systems.''
III. General Discussion of the Proposal
A. Nature of the Problem
Electrical wiring systems perform roles essential to the safety of
the entire airplane. They distribute power throughout the airplane,
transmit signals for control, and send data. Over time, as more
sophisticated computerized systems have been introduced into airplane
controls, their electrical wires, cables, and associated components
have become increasingly important to safe flight.
Historically, manufacturers have been required to provide
maintenance-related information for airplane systems. However, there
has never been a requirement for maintenance information specifically
addressing wiring systems. Since January 28, 1981, design approval
holders have been required to provide ICA for the airplane. ICA must be
prepared in accordance with Appendix H to part 25. In developing ICA,
the applicant must include certain information. This includes a
description of the airplane and its systems, servicing information, and
maintenance instructions, including the frequency and extent of
inspections necessary to provide for the continued airworthiness of the
airplane. Currently, Sec. 25.1529 includes a requirement for an FAA-
approved Airworthiness Limitations section in the ICA. This section
must list those mandatory inspections, inspection intervals,
replacement times, and related procedures approved under Sec. Sec.
25.571 and 25.981. There are no requirements for specific information
related to wiring.
Airplanes must be continually maintained and inspected, and the
information contained in the ICA is used as a basis for developing a
maintenance program. Yet the examinations of large transport airplanes
discussed earlier revealed many anomalies in electrical wiring systems
and their components, as well as contamination by dirt and debris.
Section 43.13(b) requires anyone performing maintenance or
alteration to do the work in such a manner and use materials of such a
quality that the condition of the aircraft, airframe, aircraft engine,
propeller, or appliance worked on will be at least equal to its
original or properly altered condition (with regard to aerodynamic
function, structural strength, resistance to vibration and
deterioration, and other qualities affecting airworthiness). Anyone
performing maintenance must use methods, techniques, and practices
prescribed in the current manufacturer's maintenance manual or ICA
prepared by the manufacturer, or methods, techniques, and practices
referred to in Sec. 43.13(a) as acceptable to the Administrator.
However, current practice has shown that, when wiring is inspected as
part of the maintenance program or following alterations, it is not
always cleaned appropriately for the inspection being performed.
Generally, neither FAA inspectors nor airline maintenance workers have
been fully aware of the vulnerable and critical condition of wire and
fuel tank systems. Little focus has been placed on the importance of
cleaning electrical wiring during maintenance or alteration. The result
has been to hasten the aging of wiring.
Extensive research by the FAA, in partnership with the aviation
industry and other government agencies, has shown that electrical
wiring on transport category airplanes is subject to a breakdown of
physical and functional properties. This is not just a function of
time, but also because of many stresses on the wiring. These stressors
include chafing, vibration, contamination, and temperature variation,
all of which can cause cumulative damage. Each airplane maintenance
procedure or modification, whether performed on the wiring system
itself or on surrounding components, introduces possibilities for
unintentional damage, changes to the previously approved wire design,
or contamination of the wiring systems by fluids, foreign objects, and
debris. As the aviation industry matures, there are more older
airplanes in service, and the wiring in those airplanes has had more
years of exposure to all these factors. Electrical wiring system
malfunctions resulting from inadequate design, alteration, maintenance,
inspection, and repair practices can cause incidents and accidents
involving smoke, fire, and/or loss of function.
Wire contamination is a major concern, especially in older
airplanes,
[[Page 58514]]
and it occurs in many ways. Dust, dirt, and lint from airplane carpets
and seats, lavatory waste products, hydraulic fluid, engine oil,
corrosion prevention compounds, and galley spills all collect over
time. Liquids can corrode connectors and other wiring components and
degrade wire insulation. In addition, electrical current flow in the
wiring attracts dust, dirt, and lint, and they are deposited on the
wiring system and surrounding airplane structure by cabin airflow.
Leakage of fluid lines and spills make the wiring grimy, so more dust,
dirt, and lint are attracted to them.
To fully understand why wiring system contamination is a major
problem and a potential fire hazard that could prevent the safe
operation of an airplane, it is necessary to understand the ``fire
triangle'' of combustion. The fire triangle symbolizes three elements--
oxygen, heat or ignition source, and fuel. All three are necessary for
fire to occur.
In an airplane, oxygen, the first element of the triangle, is
always present, because the heating and air-conditioning system must
provide a suitable environment for passengers. Wiring can act as an
ignition source (second element), especially if damage, such as cracked
insulation or chafing, causes a short to ground or to another
conductor, or if it causes arcing. Fuel for fire (third element) can be
present in the form of dust, dirt, lint, hydraulic fluid, engine oil,
engine fuel, and corrosion prevention compound. Eliminating or
mitigating any of these elements will help remove the fire threat.
For obvious reasons, oxygen cannot be eliminated from an airplane.
Wiring systems provide critical functions, so they cannot be eliminated
either. But their ability to act as a fire ignition source can be
mitigated by proper design, maintenance, and repair. The easiest
element to alleviate is fuel for fire. The improved maintenance
requirements in this proposal, as well as the more rigorous design
standards, are intended to address the fuel and ignition elements of
the fire triangle of combustion.
This NPRM also addresses the requirement that certain operators
incorporate ICA for their fuel tank systems into their maintenance or
inspection programs, to ensure the continued safe operation of those
design features that minimize the potential for an ignition source in
the fuel tank system. Although there are existing regulations that
require these ICA, the FAA believes, based on lessons learned from SFAR
88 and industry comments, that the existing operational rules need to
address several issues that have arisen since they were adopted. Also,
because there are elements in the fuel tank system that include wiring,
those ICA could conflict with the requirements for electrical systems
in this proposal. Additionally, the FAA believes that the compliance
times for the regulations for those two systems, wiring systems and
fuel tank systems, should be aligned.
B. Relationship of This Proposal to Other Aging Aircraft Initiatives
The FAA, as part of a broader review and realignment of its Aging
Airplane Program, has determined that certain compliance dates in
existing rules and pending proposals could be better aligned, so that
operators can comply more efficiently with the requirements during
scheduled maintenance. Compliance dates could also impact our ability
to schedule oversight programs efficiently. In addition, based on our
review, we have determined that certain substantive changes are needed
to improve the cost-effectiveness of these rules and proposals.
Therefore, we have decided to revise these requirements and proposals
and align the compliance schedules as practically as possible. Notice
of these changes and a description of our Aging Airplane Program review
appeared in the Federal Register on July 30, 2004 (69 FR 45936). The
actions affected by these revisions are this proposal and three others:
Transport Airplane Fuel Tank System Design Review,
Flammability Reduction, and Maintenance and Inspection Requirements
Special Federal Aviation Regulation (Fuel Tank Safety Rule) (final
rule).
Aging Airplane Safety (interim final rule).
Widespread Fatigue Damage (pending proposal).
To prevent any conflicts within this proposal, which affects fuel
tank wiring issues, changes to the operational requirements of the Fuel
Tank Safety Rule requiring the incorporation of fuel tank system
maintenance and inspection tasks are proposed as part of this
rulemaking.
C. Alternatives to Rulemaking
Before proposing new rulemaking, the FAA must consider alternative
ways to solve the safety issues under consideration. Following is a
brief discussion of two of the alternatives we considered during
deliberations on this rulemaking proposal.
No new regulatory action. The FAA believes that the result of no
action would be continued incidents and accidents resulting from wiring
system failures. We would continue to address these situations
``reactively'' on a case-by-case basis (as they occur) by issuing
airworthiness directives. This is unacceptable from a safety
standpoint. Improved certification regulations, inspection and
maintenance programs, and ICA for wiring systems are needed to address
the potential for similar problems arising on existing and future
designs, and to ensure their long-term safety.
Rely on voluntary compliance with the intent of the rule by
affected parties. Some in industry have suggested simply issuing ACs to
give guidance on the changes that need to be made. Issuing ACs would
depend on voluntary compliance, and would not be enforceable. While
certain members of the industry would proceed with voluntary programs,
others would not. The use of ACs alone would ensure neither consistent
results nor the achievement of the safety objectives of this proposal
for the current and future fleet. Previous voluntary safety
assessments, such as those relating to the thrust reverser and cargo
door reviews, have been difficult to complete in a timely manner
because they lacked enforceability. The proposed rules provide an
enforceable means to require timely completion of the actions
identified as necessary to address aging electrical wiring systems.
IV. Overview of Proposal
The FAA proposes several rule changes that collectively provide a
more proactive management of wiring systems. These changes would
require development and implementation of ICA for wiring systems and
subsequent incorporation of those ICA into the operators' maintenance
or inspection program. We are also proposing changes in the
certification rules to require, during design and installation of
airplane systems, more attention to conditions that could compromise
wire safety and accessibility.
The result of these changes to the maintenance and certification
programs would be to remove, as far as possible, sources of ignition
and fuel for fire from the wiring systems. In addition, a new part 25
subpart dedicated to wiring systems would be created. The current part
25 regulations for wire would be moved into this new subpart and
combined with new regulations. An alignment of the compliance times for
incorporation of the wire and fuel tank ICA would also occur to enable
a more comprehensive treatment of those ICA and accomplishment of the
maintenance instructions at time intervals consistent
[[Page 58515]]
with typical airplane maintenance checks.
The FAA believes that traditional ways of addressing wiring are no
longer enough. Because wire damage or degradation can be the result of
successive and interactive factors introduced over time, the approach
to ensuring wiring safety must be analytical, multilayered, and
proactive, rather than reactive. An analytical approach means assessing
logically the possibilities for fire occurring. A multilayered approach
means addressing multiple layers of stressors, like chafing, vibration,
temperature change, and modification that act on wiring in succession
or concurrently and can cause cumulative damage to an electrical
system. A proactive approach means addressing conditions affecting safe
flight that we know can happen--before they happen. Causes of wire
degradation must be addressed separately and collectively, and analyzed
in relation to the entire airplane. Based on the findings and research
described earlier in this document, the FAA has determined that air
carriers, operators, TC holders, supplemental type certificate (STC)
holders, repair stations, and certificated maintenance personnel need
to place more emphasis on wiring and fuel tank systems when performing
maintenance and alterations. Currently, other than the visual
inspections required by maintenance or inspection programs, maintenance
is not normally performed on these systems unless an obvious
discrepancy is identified. This proposal is designed to heighten
awareness of the criticality of wiring systems and to change the
current approach to maintaining and modifying them. Maintenance
personnel need to be aware that current industry practice for
maintenance and inspection of these systems is inadequate and must be
improved, as provided by this proposal.
The changes proposed in this NPRM were derived from the
maintenance, inspection, design, and alteration best practices
developed through extensive research by ATSRAC and other groups,
including the White House Commission on Aviation Safety and
Security,\3\ the National Science and Technology Council Committee on
Technology Wire System Safety Interagency Working Group,\4\ the IIWG,
and safety reviews required in accordance with SFAR 88.
---------------------------------------------------------------------------
\3\ ``Final Report to President Clinton, February 12, 1997,'' a
copy of which is in the docket.
\4\ ``Review of Federal Programs for Wire System Safety,''
November 2000, in the docket.
---------------------------------------------------------------------------
The following table summarizes the proposed regulatory changes that
are discussed in detail in this section.
Summary of Proposed Rulemaking in This NPRM
------------------------------------------------------------------------
Description of
Affected part of 14 CFR proposal Applies to
------------------------------------------------------------------------
1........................... Adds the
abbreviation
``EWIS''.
25.......................... Harmonization rules. Applicants for type,
amended, and
supplemental type
certificates
25.......................... New subpart H Applicants for type,
containing: New and amended, and
revised wire- supplemental type
related certificates
certification
requirements
including
requirements to
develop ICA for
electrical wiring
interconnection
systems.
25.......................... New subpart I Type certificate
containing: New holders for large
requirements to transport category
develop ICA for airplanes and
electrical wiring certain applicants
interconnection for type, amended
systems in and supplemental
accordance with type certificates
proposed Sec.
25.1539 and the
revised Appendix H
for the current
specified fleet.
Parts 121/129............... Requirement to U.S. certificate
incorporate new holders and foreign
EWIS ICA into persons operating
maintenance program U.S. registered
(included in new large transport
subparts for category airplanes
Continued
Airworthiness).
Parts 91/121/125/129........ New subparts (L, Y, U.S. certificate
M, and B holders and foreign
respectively) for persons operating
Continued U.S. registered
Airworthiness large transport
containing parts category airplanes.
121/129 EWIS ICA
requirements
(above) and:
Requirement
to incorporate fuel
tank ICA into
maintenance program.
Redesignation of
other existing
requirements into
these new subparts.
------------------------------------------------------------------------
Currently, part 25 does not have a separate subpart governing
wiring. Certification rules that apply to wiring appear throughout the
regulations, under the headings ``Design and Construction,''
``Powerplant,'' and ``Equipment.'' In some of these rules, the term
``wiring'' is not specifically used.
The discussion of proposed changes to part 25 is broken into four
parts:
Part 25 Subpart H--Electrical Wiring Interconnection
Systems (EWIS).
Part 25 Subpart I--Continued Airworthiness.
Other Proposed Changes to Part 25.
Part 25 Electrical System Harmonization Rules.
ATSRAC recommended placing part 25 wiring-related regulations into
one section. This change would increase the visibility of these
regulations and facilitate a comprehensive process for the design and
certification of wire systems. ATSRAC reviewed the current part 25 to
identify each regulation that related to wiring, either directly or
indirectly. Each wire-related regulation was then reviewed to determine
if it should be moved (in whole or in part) into the proposed new
subpart. As a result of ATSRAC's recommendations, this NPRM would
change some existing wire requirements, add new ones, and compile all
of them into a new subpart: subpart H of part 25.
No single regulation was moved in its entirety to the new subpart,
but applicable portions of regulations were moved. Some regulations
easily lent themselves to division into wire and non-wire portions,
while others did not. In some cases it was difficult to remove the
wire-related portion and maintain the continuity of the existing
regulation. In those cases, the regulation was not moved to subpart H.
Instead, the current regulation remained in place and a new subpart H
regulation was created to state the importance of wiring systems to the
safe design of the system that is the subject of the existing
regulation. Portions of some current regulations that were moved to the
new subpart were divided and distributed among
[[Page 58516]]
several new subpart H sections to follow the logical structure of the
new subpart. Accordingly, there is not always a one-to-one
correspondence between the existing regulations and the new subpart H
regulations. A table showing the correlation between proposed new
regulations and the existing regulations can be found in APPENDIX B.
The table in APPENDIX C compares the existing regulations to the
proposed new ones. The APPENDIX D table shows which of the current
wire-related rules must be changed to accommodate the new subpart and
which will remain the same.
Adoption of the proposed new and revised requirements and advisory
material would help prevent future occurrences of the types of
incidents and accidents described in this NPRM. The creation of a new
part 25 subpart for all existing, revised, and new wire system
certification requirements would strengthen the role of properly
designed, installed, and maintained wire systems in increasing the
safety of flight. It would also provide the regulatory tools to help
ensure this outcome and locate all applicable regulations in a single
place that is easy to reference and use.
Certain vintage airplanes type certificated before 1958, the
beginning of the jet age, would be excluded from the requirements of
this proposal. They are named in paragraph (f) of Sec. 25.1805 and in
the final paragraph of each of the proposed fuel tank and EWIS
operating rules. There are no known reciprocating-powered transport
category airplanes currently in scheduled passenger service, and the
few remaining in cargo service would be excluded. Compliance is not
required for these specific older airplanes because their advanced age
or small numbers would likely make compliance economically impractical.
V. Section-by-Section Discussion of Proposed Rules
The FAA proposes to add the abbreviation for electrical wiring
interconnection systems (EWIS) to 14 CFR part 1--Definitions and
Abbreviations. The purpose of this addition is to ensure the use of a
common term for EWIS throughout the regulations. More detailed analysis
of the other proposed changes and additions is outlined below.
A. Part 25 Subpart H--Electrical Wiring Interconnection Systems (EWIS)
The proposed subpart H consists of relocated, revised, and new
regulations about EWIS. Unless we say otherwise, our purpose in moving
requirements to subpart H is to ensure their application to EWIS. We do
not intend to change their legal effect in any other way.
Section 25.1701 Definition
Proposed Sec. 25.1701 would define what constitutes an EWIS for
the purposes of complying with the proposed subpart H requirements and
other EWIS-related requirements of parts 25, 121, and 129.
Current regulations do not provide a definition of a wiring system.
Without this definition, the proposed rules could be inconsistently
applied to various wire-related components. To completely address the
safety issues associated with wiring systems, requirements must address
not only the wiring itself, but also components and devices that are
required to adequately install and identify each wire. Various
components and devices needed to route and identify wires are critical
in ensuring that a proper electrical interconnection is made and
maintained.
For the purposes of this NPRM, the term ``wire'' means bare and/or
insulated wire used for the purpose of electrical energy transmission,
grounding, or bonding. This includes electrical cables, coaxial cables,
ribbon cables, power feeders, and databuses.
A proper electrical interconnection between two or more points
requires more than just wire. Making the connection in a manner that
ensures both functionality and safety requires various types of
components, of which wire is one. Therefore, a clear definition of an
electrical interconnection is necessary. The proposed regulation
provides this and at the same time introduces the term ``electrical
wiring interconnection system (EWIS)'' to describe that
interconnection. The term EWIS means any wire, wiring device, or
combination of these, including termination devices, installed in the
airplane for transmitting electrical energy between two or more
termination points. The proposed regulation expands on this basic
statement to clearly identify which wire-related components are
included in the EWIS definition and which are not. Most wires are
routed with other wires that make up wire bundles and cable assemblies
(or ``looms,'' as they are sometimes called). A single wire may also be
routed separately. The same definition of an EWIS is applied to a
single wire or to a bundle containing hundreds of wires.
To complete an electrical connection, various types of connectors
are necessary. Examples are MS connectors (MS means military
specification), D-subminiature connectors, and rack and panel
connectors. Any connector used to complete an electrical connection is
included in the EWIS definition. The exception to this is the mating
connection on those devices that are excluded from the proposed
definition. The excepted devices are addressed later in this
discussion.
Connector accessories fall under the definition of EWIS. Such
accessories include, but are not limited to, backshells, strain
reliefs, grommets, and sealing plugs. Electrical connections to devices
such as relays, interrupters, switches, contactors, terminal blocks,
and feed-through connectors are parts of an EWIS. For example, the
connection device on a relay is considered part of the EWIS, but the
relay mechanism is not, because it is a termination point. A splice can
be considered an electrical connector because it performs the same role
as other connection devices by providing an electrical connection
between two or more wires. The failure of a splice or relay connection
could create a hazardous situation by exposing bare conductors or
impairing system functionality.
Although a bus bar is not a ``connector'' in the traditional sense,
it is a collector and distribution device for electrical energy and
thus must be treated as part of an EWIS.
Wire or wire bundles require devices to physically route and
support them, such as clamps, brackets, standoffs, and other such
components. These are included in the EWIS definition. Cable ties are
included because they are used to hold multiple wires together and in
place. The failure of one or more of these EWIS components could affect
the ability of the wire to perform its intended function. It could
cause collateral damage to other wires in the same or adjacent bundles
or cause the bundle to fail in a way that would cause structural damage
or ignite flammable material, fluid, or vapors in the area.
Some wires must pass through pressure bulkheads, so a pressure seal
is needed. Failure of a pressure seal could cause damage to the wires
in the wire bundle and affect the functioning of the system they
support. Some wire bundles use shields or braids to protect them from
electromagnetic radiation, lightning, abrasion, and other types of
physical damage. Failure of the shields or braid could cause, or allow,
the wires to be damaged. It could also allow unwanted electrical energy
to be coupled into systems and cause system malfunction. Thus, shields,
braids, and pressure seals must be considered part of the EWIS and
treated as such.
Sometimes adequate physical separation distance is not possible,
and some sort of protective sleeving may be
[[Page 58517]]
used. Since the sleeving is used to achieve separation, it must be
considered part of the EWIS.
Conduits are included in the proposal because they are used to
provide protection for wires as well as provide physical separation.
Conduits that have electrical termination for bonding are considered
part of an EWIS because the failure of the bonding could create a
hazardous situation.
The definition of an EWIS includes labels or other means used for
identification. This supports the proposed Sec. 25.1711 requiring new
identification criteria for wires and other EWIS components. Discussion
of the proposed labeling requirements appears under the heading for
Sec. 25.1711.
The proposed regulation does not cover portable, carry-on, or other
electrical equipment not certified for installation on the airplane
under part 25. Examples of items not included are laptop computers and
portable audio and/or video or other consumer devices typically carried
on-board by passengers for personal use. Increasingly, flight and cabin
crew are using laptop computers in the performance of their duties. As
stated, laptops are not part of the EWIS definition, but any electrical
connection used to support power and/or signal transmission that is
part of the airplane TC, and that is used for the laptop or other
carry-on items, is covered by the proposed definition.
The proposed EWIS definition does not cover fiber optic cable
because fiber optic cable does not transmit electrical energy. But
since fiber optics can provide functions (for example, data
transmission) similar to those provided by wire, it is being expressly
eliminated from the EWIS definition to avoid confusion.
The proposed definition excludes electrical wiring interconnection
system components inside avionics equipment (high-frequency
communication radio or flight data recorder, for instance), or the
mating electrical connectors mounted on that equipment. Such equipment
is produced by various manufacturers for use on a broad range of
airplane models and is designed and built to various performance and
environmental specifications. Environmental testing, either by means of
RTCA (Radio Technical Commission for Aeronautics) Document No. RTCA DO-
160, EUROCAE 55 specification (specification of the European
Organization for Civil Aviation Equipment), or other environmental
qualification procedures approved by the FAA, ensures that the EWIS
contained within avionics equipment is robust and well suited for the
airborne environments in which it will be operated.
This proposal also does not apply to miscellaneous electrical
equipment if that equipment has been adequately qualified to
environmental conditions and testing procedures approved by the FAA,
unless that equipment is specifically included in the proposed Sec.
25.1701 as discussed in the following paragraph.
The definition of EWIS includes electrical wiring interconnection
system components inside shelves, panels, racks, junction boxes,
distribution panels, back-planes of equipment racks including circuit
board back-planes, and wire integration units. We have included the
components in this type of equipment because it, unlike avionics
equipment, is typically designed and made for a particular airplane
model or series of models. The same requirements that apply to airplane
EWIS components must also be applied to the components inside that
equipment. Avionics components must be sent back to their manufacturer
or a specialized repair shop for service. But this type of equipment is
maintained, repaired, and modified by the same personnel who maintain,
repair, and modify the EWIS in the rest of the airplane. In an
electrical distribution panel system, for example, separation must be
designed and maintained within the panel just as in the EWIS leading up
to that panel. Identification of components inside the panel is just as
important as for those outside the panel since the wiring inside the
panel is treated much the same. Also, while this type of equipment is
designed for its intended function and is manufactured and installed to
the same standards as other EWIS, it is typically not qualified to an
environmental standard such as RTCA DO-160.
Section 25.1703 Function and Installation: EWIS
Proposed Sec. 25.1703 would require that applicants select EWIS
components that are of a kind and design appropriate to their intended
function. Factors such as the components' design limitations,
functionality, and susceptibility to arc tracking and moisture must be
considered when selecting EWIS components.
Section 25.1301 requires that each item of installed equipment be
of a kind and design appropriate to its intended function, be labeled
(identified), be installed according to any limitations specified for
it, and function properly when installed. This is a general ``catch-
all'' regulation applicable to equipment and systems certified under
subpart F. Because of its generality and the fact that the FAA has not
published any advisory circular for this rule, Sec. 25.1301 has not
been applied in a standardized way. Currently, Sec. 25.1301 is
applicable to wire and its associated components but it does not
provide sufficient wire-specific requirements to ensure proper function
and installation of EWIS. It does not adequately cover all factors that
need to be considered when selecting, identifying, and installing
wiring components.
The requirements of Sec. 25.1301 are the basis for the new Sec.
25.1703, but those requirements are supplemented by new ones.
Requirements from other existing sections are also moved into the new
regulation, so that the proposed rule would specifically apply to EWIS
components. Adoption would ensure that the selection of wires and other
EWIS components, and their installation, are carried out in a safe,
consistent, and standardized manner.
Section 25.1703(a)(1) would require that each EWIS component be of
a kind and design appropriate to its intended function. While Sec.
25.1301(a) contains the same requirements, Sec. 25.1703(a)(1) is
specific to EWIS components. In this context, the requirement means
that components must be qualified for airborne use, or otherwise
specifically assessed as acceptable for their intended use. To be
``appropriate'' means that the equipment is used in a manner for which
it was designed. For example, a wire rated at 150 degrees Celsius would
not be appropriate for installation in an airplane zone where the
temperature exceeds 150 degrees Celsius. Wire and other components made
for household or consumer products use would not be appropriate for
airborne use because they are manufactured for the consumer market and
not for use in an airborne environment. Exceptions to this would be
wire or other consumer components shown to comply with all the
applicable airworthiness requirements of part 25. In the past this
showing of compliance has proven to be difficult because manufacturers
of consumer products have been reluctant to modify their designs to
accommodate aviation use. Aviation use of consumer products represents
too small a market.
Other factors that must be considered for EWIS component selection
are mechanical strength, voltage drop, required bend radius, and
expected service life. Expected service life means the expected service
lifetime of the EWIS. This is not normally less than the expected
service life of the aircraft structure. If the expected service life
requires that all or some of the EWIS components be replaced at certain
[[Page 58518]]
intervals, then these intervals must be specified in the ICA as
required by Sec. 25.1529.
Section 25.1703(a)(2) requires that EWIS components be installed
according to their limitations. As used here, limitations means the
design and installation requirements of the particular EWIS component.
Examples of EWIS component limitations are maximum operating
temperature, degree of moisture resistance, voltage drop, maximum
current-carrying capability, and tensile strength. Section 25.1301(c)
contains that requirement, but fails to specifically address the unique
characteristics of EWIS. EWIS component selection and installation
design must take into account various environmental factors including,
but not limited to, vibration, temperature, moisture, exposure to the
elements or chemicals (de-icing fluid, for instance), insulation type,
and type of clamp. For example, wire bundle adhesive clamps are known
to work loose during aircraft operation. Attention must be given to the
selection of and methods of affixing this type of wire bundle support
and it must be shown that this type of clamp is appropriate for the
environment in which it will be used.
Section 25.1703(a)(3) would require that EWIS function properly
when installed. This is the same requirement as Sec. 25.1301(d).
However, the Sec. 25.1301(d) requirement is so general that it is
applied in a nonstandardized manner. Sometimes the term ``function
properly when installed'' has been interpreted to mean that even non-
safety-related functions of a given system must function in the manner
for which it was designed. The key word in understanding the intent of
this proposed section is ``properly,'' as that relates to airworthiness
of the airplane in which the electrical wiring interconnection systems
are installed. For an EWIS component to function properly means that it
must be capable of safely performing the function for which it was
designed. For example, the fact that an airplane's in-flight
entertainment (IFE) system fails to deliver satisfactory picture or
sound quality is not what the term ``properly'' refers to and is not a
certification issue. However, the failure of an EWIS component has the
potential for being a safety hazard whether it is part of a safety-
related system or an IFE system. Therefore, EWIS components must always
function properly when installed, no matter what system they are part
of. The guidance material being prepared to accompany the proposed
subpart H, AC 25,17XX, ``Certification of Electrical Wiring
Interconnection Systems on Transport Category Airplanes,'' will clarify
these distinctions.
Section 25.1703(a)(4) is a new requirement to ensure that EWIS
components be designed and installed so mechanical strain is minimized.
This means the EWIS installation must be designed such that strain on
the wires would not be so great as to cause wire or other components to
fail. This requirement would ensure that adequate consideration is
given to mechanical strain when selecting wire and cables, clamps,
strain reliefs, stand-offs, and other devices used to route and support
the wire bundle.
Proposed Sec. 25.1703(b) would require that selection of wires for
installation takes into account known characteristics of different wire
types in relation to each specific application, to minimize risk of
damage. It is important to select the aircraft wire type whose
construction matches the application environment. The wire type
selected must be constructed for the most severe environment likely to
be encountered in service. Among other things, the proposed section
would ensure that insulation types susceptible to arc tracking be used
only in environments that will minimize the likelihood of that
phenomenon. Arc tracking is a phenomenon in which a conductive carbon
path forms across an insulating surface. A breach in the insulation
allows arcing. The arcing carbonizes the insulation. The carbon residue
is electrically conductive. The carbon path then provides a short
circuit path through which current can flow. This can occur on either
dry or wet wires. Certain types of wire insulation are more susceptible
to arc tracking than others. Wire insulated with aromatic polyimide is
one type that is susceptible to arc tracking. While this type of
insulation is well suited for use in very low or high temperature
environments, it generally should not be used in areas of an airplane
prone to excessive moisture or vibration, such as those areas
designated as severe wind and moisture problem (SWAMP) areas without
taking into account this insulation property's unique characteristics.
Installations exposed to vibration and constant flexing in a moisture-
prone area would need wire type suitable for that environment. Proposed
Sec. 25.1703(c) would require that design and installation of the main
power cables allow for a reasonable degree of deformation and
stretching without failure. This requirement now resides in Sec.
25.869(a)(3).
Proposed Sec. 25.1703(d) requires that EWIS components located in
areas of known moisture build-up be adequately protected to minimize
moisture's hazardous effects. This is to ensure that all practical
means are used to ensure damage from fluid contact with components does
not occur. Wires routed near a lavatory, galley area, hydraulic lines,
severe wind and moisture problem areas such as wheel wells and wing
trailing edges, and any other area of the airplane where moisture
collection could be a concern must be adequately protected from
possible adverse effects of exposure to the types of moisture in these
areas.
If a TC includes subpart H in its certification basis, the TC
holder would have to show compliance with the proposed EWIS
requirements. For future modifications of those TCs, use of the same
design practices as those used by the TC holder will enable the
modifier to substantiate compliance with the subpart H requirements
based on a comparison with the TC holder's methods. If modifiers choose
to deviate from those design practices, they would have to substantiate
compliance independently. They would also have to consider the design
practices used by the TC holder in order to justify their own choice of
components.
In summary, these new rules would require the designer and
installer to be careful in wire type choices, system design, and
installation design. The existing Sec. 25.1301 would be amended to
contain a reference to Sec. 25.1703 for EWIS component requirements.
Section 25.1705 System Safety: EWIS
Proposed Sec. 25.1705 would require applicants to perform a system
safety assessment of the EWIS. The safety assessment must consider the
effects that both physical and functional failures of EWIS would have
on the airplane's safety. Based on that safety assessment, it must be
shown that each EWIS failure considered to be hazardous is extremely
remote. Each EWIS failure considered to be catastrophic must be shown
to be extremely improbable and not result from a single failure.
The current regulation requiring system safety assessments is Sec.
25.1309. But current Sec. 25.1309 practice does not lead to the type
of analysis that fully ensures all EWIS failure conditions affecting
airplane-level safety are considered. This is because the current Sec.
25.1309(a) only covers systems and equipment that are ``required by
this subchapter,'' and wiring for nonrequired systems is sometimes
ignored. The current safety analysis requirements of Sec. 25.1309(b)
and (d) have not always been applied to wire associated with the
airplane systems that are covered by the
[[Page 58519]]
same rule. When they are, there is evidence of inadequate and
inconsistent application. This is especially true for miscellaneous
electrical equipment that is not required, such as IFE systems.
Traditional thinking about these nonrequired systems has been that,
since they are not required, and the function they provide is not
necessary for the safety of the airplane, their failure could not
affect the safety of the airplane. This is not a valid assumption
because failure of an electrical wire can have hazardous or even
catastrophic results regardless of the system it is associated with.
Wire failure can cause serious physical and functional damage whether
the wire or other EWIS components are associated with an autoland
system or an IFE system. An example of this is arcing from a shorted
wire cutting through flight control cables.
The Aviation Rulemaking Advisory Committee (ARAC), based on the
work of its System Design and Analysis Harmonization Working Group, has
made recommendations to the FAA for changes to the current Sec.
25.1309. We are evaluating those recommendations. (A copy of those
recommendations has been placed in the docket for reference.) We have
considered the ARAC recommendations in developing the proposed Sec.
25.1705.
One of the factors we considered in developing the proposed Sec.
25.1705 is that the proposed ARAC revisions to Sec. 25.1309 would
exempt certain airplane systems, including the EWIS components
associated with those systems, from having to comply with its
requirements. Specifically, ARAC recommends that jamming of flight
control surfaces or pilot controls covered by Sec. 25.671(c)(3) be
exempt from the requirements of Sec. 25.1309. Single failures covered
by Sec. 25.735(b)(1) and the failure effects covered by Sec. Sec.
25.810(a)(1)(v) and 25.812 would also be excepted from the revision to
Sec. 25.1309(b) recommended by ARAC. This includes wiring or other
EWIS components associated with those systems. In part, proposed Sec.
25.1705 would ensure coverage of the EWIS associated with those
systems.
There are many examples of inadequate EWIS designs that have later
been determined to be unsafe. Adoption of proposed Sec. 25.1705 would
help ensure that those unsafe design practices are not repeated in the
future by requiring that EWIS failure conditions affecting airplane-
level safety are fully considered. The current Sec. 25.1309 does not
provide that assurance.
The FAA has issued over 100 wire-related airworthiness directives
(AD) since 1998. Over 50 of those were issued since 1999 to correct
wiring deficiencies on the Model MD-11 airplane as delivered by the
manufacturer. Airplanes as delivered from all transport category
airplane manufacturers have been the subject of mandatory corrective
action to correct safety-related wiring problems.
Similarly, the FAA has issued many ADs to correct unsafe EWIS
installations because of postdelivery modifications. One example of
this involves the IFE system installed on the Swissair MD-11 airplane
that crashed off the coast of Nova Scotia and was discussed previously
in this document. That modification is a clear case of not considering
the effect that EWIS failures can have on airplane safety. The airplane
was modified using the supplemental type certification process to add
the IFE system. That system contained roughly 750 separate electronic
boxes and was installed without an adequate safety assessment per Sec.
25.1309. Although this IFE system consumed relatively large amounts of
electrical power and its components and wiring were distributed
throughout, below, and above the entire passenger cabin, the applicant
did not thoroughly address the safety implications of routing the
system wire in the same bundles as wire from other airplane systems,
thus raising a concern for common cause failure to multiple essential
systems. In many instances the applicant could not identify what
airplane systems were associated with the wire in the bundles modified
to route the IFE wiring. With the adoption of the proposed Sec.
25.1705, this IFE system, as designed and installed on an airplane with
the proposed subpart H in its type certification basis, would be
subjected to a more rigorous safety assessment that would identify any
inappropriate routing and force a design change.
Many other examples of type design modifications provide evidence
that modifiers do not always give due consideration to the impact on
safety that installation of a new or modified system may have.
Modifiers continue to route the EWIS needed for modifications with, or
in close proximity to, wiring from other airplane systems without
identifying protection mechanisms for those systems. The current Sec.
25.1309 and revisions to it recommended by ARAC do not contain
sufficient requirements to ensure such modifications maintain the level
of safety intended by the regulation.
Accordingly, a more comprehensive and specific safety assessment
regulation for EWIS is necessary. The objective of the proposed Sec.
25.1705 is to focus attention on EWIS and the safety issues associated
with them by using the concepts of Sec. 25.1309 to provide for
consistent use of a more thorough and structured analysis of aircraft
wiring and its associated components.
The integrated nature of wiring and the potential severity of
failures demand a more structured safety analysis approach than that
traditionally used under the current, or the ARAC's proposed revision
to, Sec. 25.1309. There are more failure modes that need to be
addressed than have been addressed previously with traditional analyses
(arcing events that occur without tripping circuit breakers, resulting
in complete wire bundle failures and fire; or wire bundle failures that
lead to structural damage, for example). Current Sec. 25.1309 system
safety assessments typically evaluate effects of wire failures on
system functions. But they have not considered physical wire failure as
a cause of the failure of other wires within the EWIS. The traditional
assessments look at external factors like rotor burst, lightning, and
hydraulic line rupture, but not at internal factors, like a single wire
chafing or arcing event, as the cause of the failure of functions
supported by the EWIS. Compliance with the proposed Sec. 25.1705 would
require addressing those failure modes at the airplane level. This
means that EWIS failures would need to be analyzed to determine what
effect they would have on the safe operation of the airplane.
The proposed rule language is consistent with Sec. 25.1309 and is
meant to work in conjunction with the Sec. 25.1309 assessments
performed on airplane systems. It would require that the probability of
a hazardous failure condition be extremely remote and that the
probability of a catastrophic failure condition be extremely improbable
and not result from a single failure. The terminology and meaning of
the classifications of EWIS failure conditions are identical to those
proposed by ARAC in August 2002. The proposed AC produced by that
working group discussing this, titled ``System Design and Analysis,''
is in the docket for this NPRM. The following table identifies and
explains the failure condition terms.
[[Page 58520]]
Classification of Failure Conditions
------------------------------------------------------------------------
Term Explanation
------------------------------------------------------------------------
No Safety Effect.................. Failure conditions that would have
no effect on safety; for example
failure conditions that would not
affect the operational capability
of the airplane or increase
flightcrew workload.
Minor............................. Failure conditions that would not
significantly reduce airplane
safety, and involve flightcrew
actions that are well within their
capabilities. Minor failure
conditions may include, for
example:
a slight reduction in
safety margins or functional
capabilities;
a slight increase in
flightcrew workload, such as
routine flight plan changes; or
some physical discomfort to
passengers or cabin crew.
Major............................. Failure conditions that would reduce
the capability of the airplane or
the ability of the flightcrew to
cope with adverse operating
conditions to the extent that there
would be, for example:
a significant reduction in
safety margins or functional
capabilities;
a significant increase in
flightcrew workload or in
conditions impairing flightcrew
efficiency;
discomfort to the
flightcrew; or
physical distress to
passengers or cabin crew, possibly
including injuries.
Hazardous......................... Failure conditions that would reduce
the capability of the airplane or
the ability of the flightcrew to
cope with adverse operating
conditions to the extent that there
would be, for example:
a large reduction in safety
margins or functional capabilities;
or
physical distress or
excessive workload such that the
flightcrew cannot be relied upon to
perform their tasks accurately or
completely; or
serious or fatal injuries
to a relatively small number of
persons other than the flightcrew.
Catastrophic...................... Failure conditions that would result
in multiple fatalities, usually
with the loss of the airplane.
(Note: A catastrophic failure
condition was defined differently
in previous versions of Sec.
25.1309 and in accompanying
advisory material as ``a failure
condition that would prevent
continued safe flight and
landing.'')
------------------------------------------------------------------------
The proposed Sec. 25.1705 would complement the Sec. 25.1309
assessments by raising the quality of the safety assessment with
respect to EWIS failures that would not be identified using the
traditional methods of compliance with Sec. 25.1309. The analysis
required to show compliance with the proposed regulation is based on a
qualitative approach to assessing EWIS safety as opposed to a numerical
probability-based quantitative analysis. The intent is not to examine
each individual wire and its relation to other wires, but rather to
ensure that there are no unacceptable hazards to the airplane. This
does not preclude the possibility that, should the analysis identify a
failure in a given wire bundle or component(s) that may lead to a
catastrophic failure condition, the design mitigation process may lead
to performing a complete analysis of each wire in the relevant bundle.
The type of analysis used to show compliance with the proposed
Sec. 25.1705 can vary depending on the knowledge of the designers or
modifiers of an EWIS. As stated earlier, it is important that there is
thorough knowledge of what systems and functions the other wires in the
same and surrounding bundles support. In the case of a post-TC
modification, without this information it would be impossible to state
that the modified system could not fail in a way that would cause a
hazardous or catastrophic event. If this information is not available
to the modifier, then the EWIS system must be designed to accommodate
this lack of knowledge. This would typically mean that wire being added
for the modification would need to be routed separately from existing
airplane wiring.
Flowchart 1 and Flowchart 2, contained in Appendix E of this
notice, illustrate the type of analysis necessary to show compliance
with the proposed Sec. 25.1705. Two separate cases are considered.
Flowchart 1 is applicable to pre-type-certification work and to TCs and
STCs when the modifier has all the data necessary to perform the
analysis. If the analysis is conducted according to this flowchart, the
available data must include identification of systems supported by the
EWIS under consideration for modification and the functions associated
with them. The original aircraft manufacturer has most of this data and
would normally follow the Flowchart 1 method. However, this may not
always be the case when the manufacturer modifies an airplane that has
been previously modified by another party.
The analysis depicted in Flowchart 2 would apply to modifiers for
post-TC modification who cannot identify the systems or functions
contained in EWIS being considered for modification.
In both analyses, EWIS functional and physical failures are
addressed. It is the physical portion that has been neglected in past
system safety analyses. The proposed regulation would require an
applicant to identify any physical failure of EWIS that can cause
damage to co-located EWIS or other surrounding systems or structure, or
injury to people. Once those physical failures are identified, their
severity can be determined and design mitigation strategies can be
developed and applied. The process is repeated until all known unsafe
features are eliminated. The difference between the processes
identified in the two flowcharts is that in Flowchart 1, all the
systems and associated functions whose wires are in a bundle are known.
In Flowchart 2, new wire is routed separately from existing wire.
Otherwise, the analysis is the same.
In summary, the need for this new regulation is shown by experience
on the part of the FAA and other governmental regulatory authorities
and by service histories. Many wire-related incidents and accidents
have occurred. Post-TC modifications have repeatedly introduced wiring
safety problems. Airplane manufacturers have delivered airplanes that
have wiring problems when they leave the factory, or such problems have
later developed in service, as evidenced by resulting mandatory
corrective actions. Adoption of this proposal would ensure that such
problems are fully considered and addressed as part of the type
certification process.
Section 25.1709 System Separation: EWIS
Proposed Sec. 25.1709 would require applicants to design EWIS with
appropriate separation to minimize the possibility of hazardous effects
upon the airplane or its systems.
Safe operation of airplanes depends in part on the safe transfer of
electrical energy, a function provided by airplane EWIS. If an EWIS
failure should occur, the separation between the failed EWIS and other
EWIS and airplane systems
[[Page 58521]]
plays an important role in ensuring that any hazardous effects of the
failure are mitigated to an acceptable level. Thus, it is vital to
design and install wiring systems with adequate separation from those
systems whose interaction with the wire could create hazardous effects.
Currently, part 25 certification rules do not adequately address wire
system separation. The rules currently used to require system
separation are Sec. 25.1353(a), (b), and (c), but service experience
has shown that compliance with these requirements, with regard to
wiring systems, has not always been adequate. This is due in part to
their lack of specific wording about which wiring systems are covered
and which systems those wires are meant to be separated from. The
proposed rule corrects these inadequacies by stating specifically that
it applies to each EWIS on the airplane, and mandating specific
separation requirements for certain airplane systems known to have
potential for creating a hazardous condition. The term ``hazardous
condition'' in this proposed rule is used in a different context than
it is used in the proposed Sec. 25.1705. Proposed Sec. 25.1705 uses
the terms ``hazardous'' and ``catastrophic'' in the context of
assigning a numerical probability to failures that can cause a failure
condition. Hazardous failure conditions and catastrophic failure
conditions are defined in the discussion of the proposed Sec. 25.1705.
In proposed Sec. 25.1709, the term hazardous condition means that the
applicant must perform a qualitative design assessment of the installed
EWIS. This assessment would involve using reasonable engineering and
manufacturing judgment and assessing relevant service history to decide
whether an EWIS, any other type of system, or any structural component
could fail in such a way that a condition affecting the airplane's
ability to continue safe operation could result. A numerical
probability assessment may still be required under the requirements of
the proposed Sec. 25.1705 if the airplane-level functional hazard
assessment identifies failures that could affect safe operation of the
airplane.
To illustrate the type of assessment required by proposed Sec.
25.1709, consider the following simple example involving the use of
wire bundle clamps. Clamps are used to secure a wire bundle to
structure in order to hold the bundle in place and route the bundle
from one location to another along a predetermined path. An airplane
manufacturer, using the criteria contained in the proposed advisory
material for 25.1709, determines that a 2-inch separation from
hydraulic lines is necessary. The manufacturer further decides that one
clamp every 10 inches is needed to maintain that separation. However,
there is one localized area where a single clamp failure would
potentially create a hazard. This is because the area in question is a
high vibration, high temperature area, subject to exposure to moisture.
So the clamp in this particular area is exposed to severe environmental
conditions that could lead to its accelerated degradation. The
manufacturer decides that using just a single clamp every 10 inches in
this area would not suffice to preclude a hazardous event. The
manufacturer prescribes use of double clamps every 10 inches in that
area.
The requirements of proposed Sec. 25.1709 do not preclude use of
valid component failure rates if the applicant chooses to use a
probability argument in addition to the design assessment to
demonstrate compliance. It also does not preclude the FAA from
requiring such an analysis if the applicant cannot adequately
demonstrate that hazardous conditions will be prevented solely by using
the qualitative design assessment.
As used in the proposed rule, the term ``separation'' is a measure
of physical distance. The purpose of separation is to prevent hazards
of arcing between wires in a single bundle, between two or more
bundles, or between an electrical bundle and a non-electrical system or
structure. In some cases, the proposal would allow separation to be
achieved with a barrier or other means shown to be at least equivalent
to the necessary physical distance. However, distance separation is
preferred because service experience shows that use of barriers such as
conduits can cause wire damage or lead to maintenance errors. In some
cases, wire bundle sleeving is used to provide separation, although the
sleeving itself is susceptible to the same types of damage as wire
insulation.
Determining the necessary amount of physical separation distance is
essential. However, the proposed rule does not mandate specific
separation distances because each system design and airplane model can
be unique, and because manufacturers have differing design standards
and installation techniques. Instead it requires that the chosen
separation be adequate so that an EWIS component failure will not
create a hazardous condition. The following factors must be considered
when determining the separation distance:
(1) The electrical characteristics, amount of power, and severity
of failure condition of the system functions performed by the signals
in the EWIS and adjacent EWIS.
(2) Installation design features, including the number, type, and
location of support devices along the wire path.
(3) The maximum amount of slack wire resulting from wire bundle
build tolerances and other wire bundle manufacturing variabilities.
(4) Probable variations in the installation of the wiring and
adjacent wiring, including position of wire support devices and amount
of wire slack possible.
(5) The intended operating environment, including amount of
deflection or relative movement possible and the effect of failure of a
wire support or other separation means.
(6) Maintenance practices as defined by the airplane manufacturer's
standard wiring practices manual and the ICA required by Sec. 25.1529
and proposed Sec. 25.1739.
(7) The maximum temperature generated by adjacent wire/wire bundles
during normal and fault conditions.
The FAA recognizes that some airplane models may have localized
areas where maintaining the minimum physical separation distance is not
feasible. In those cases, other means of ensuring equivalent minimum
physical separation may be acceptable, if testing or analysis
demonstrates that safe operation of the airplane is not jeopardized.
The testing or analysis program must be conservative and consider the
worst possible conditions.
Paragraphs (a), (b), (c), and (d) of proposed Sec. 25.1709 contain
EWIS-related requirements derived from the existing regulations
applying to electrical power generation systems and electrical
equipment and installations (Sec. Sec. 25.1351 and 25.1353). Section
25.1351 does not need any revision to support the proposed Sec.
25.1709, but Sec. 25.1353 is amended to reference Sec. 25.1709.
The proposed requirements of Sec. 25.1709(a) were derived from
existing Sec. 25.1353(a). While the requirements of Sec. 25.1353(a)
are retained, the portion of that requirement applicable to wiring has
been moved to the proposed Sec. 25.1709(a). Further clarification of
the requirement is also included in the proposal. Section 25.1353(a)
states ``* * * wiring must be installed so that operation of any one
unit or system of units * * *.'' Proposed section 25.1709(a) expands on
the term ``operation'' to state that it means ``operation under normal
and failure conditions as defined by Sec. 25.1309.''
Proposed section 25.1709(b) would require that each EWIS be
designed and
[[Page 58522]]
installed so that any electrical interference likely to be present in
the airplane will not result in hazardous effects on the airplane or
its systems. This proposed requirement is based on new text recently
added to Sec. 25.1353(a) to harmonize part 25 with the existing text
of the JAA JAR 25.1353(a).\5\ The text of JAR 25.1353(a) requires that
any electrical interference likely to be present in the airplane must
not result in hazardous effects on the airplane or its systems except
under extremely remote conditions. The proposed Sec. 25.1709(b) is
recognition of the fact that electrical interference can be introduced
into airplane systems and wiring by coupling between electrical cables
or between cables and coaxial lines, as well as by the other equipment
that is the subject of Sec. 25.1353(a). The proposed requirement does
not adopt the JAR clause ``except under extremely remote conditions.''
This is because the intent of the requirement is not to require a
numerical probability assessment of the likelihood of electrical
interference or its consequences as described previously. Rather it is
meant to convey that under failure conditions that may be caused by
electrical inference, the resultant effects should not be such as to
prevent continued safe flight of the airplane.
---------------------------------------------------------------------------
\5\ The JAA is the Joint Aviation Authority of Europe and the
JAR is its Joint Aviation Requirements, the equivalent of our
Federal Aviation Regulations. In the time since these proposals were
developed, in 2003, the European Aviation Safety Agency (EASA) was
formed. EASA is now the principal aviation regulatory agency in
Europe, and we intend to continue to work with them to ensure our
proposal is also harmonized with its Certification Specifications
(CS). But since the harmonization efforts involved in developing
this proposal occurred before EASA was formed, it was the JAA that
was involved with them. So while the JAR and CS are essentially
equivalent, and in the future we will be focusing on the CS, it is
the JAR that will be referred to in the historical background
discussions in this proposal.
---------------------------------------------------------------------------
Proposed section 25.1709(c) contains the wire-related requirements
of the current Sec. 25.1353(b). These requirements have been expanded
to add that not only wires and cable carrying heavy current are
covered, but their associated EWIS components are covered as well. The
proposal prescribes that any required physical separation must be
achieved either by separation distance or by barrier or other means
shown to be at least equivalent to an adequate separation distance.
Proposed section 25.1709(d) contains wire-related requirements of
existing Sec. Sec. 25.1351(b)(1) and (b)(2) and would introduce
additional requirements. To show compliance with Sec. 25.1709(d), EWIS
components associated with the generating system must be considered
with the same degree of attention as other components of the system,
such as the electrical generators. The proposal prescribes that any
required physical separation must be achieved either by separation
distance or by a barrier or other means shown to be at least equivalent
to an adequate separation distance. Paragraph (d)(1) would introduce a
requirement to prohibit the airplane's independent electrical power
sources from sharing a common ground terminating location. Paragraph
(d)(2) would prohibit the airplane's static grounds from sharing a
common ground terminating location with any of the airplane's
independent electrical power sources. These two new requirements would
help to ensure the independence of separate electrical power sources
and to prevent introduction of unwanted interference into airplane
electrical power systems from other airplane systems.
Paragraphs (e), (f), (g), and (h) of proposed Sec. 25.1709 contain
EWIS-related requirements from Sec. 25.1353(d)(3). These paragraphs
contain specific separation requirements for the airplane's fuel,
hydraulic, oxygen, and waste/water systems. They require that EWIS have
adequate separation from those systems except to the extent necessary
to provide any required electrical connection to them. These paragraphs
require that EWIS be designed and installed with adequate separation so
a failure of an EWIS component will not create a hazardous condition
and any leakage from those systems (i.e., fuel, hydraulic, oxygen,
waste/water) onto EWIS components will not create a hazardous
condition. The proposed requirements recognize the potential
catastrophic hazard that could occur should an arcing fault ignite a
flammable fluid like fuel or hydraulic fluid. An arcing fault has the
potential to puncture a line associated with those systems if adequate
separation is not maintained. If there is leakage from one of those
systems and an arcing event occurs, fire or explosion could result.
Similarly, leakage from the water/waste system can cause damage to EWIS
components and adversely affect their integrity. An EWIS arcing event
that punctures a water or waste line could also introduce fluids into
other airplane systems and create a hazardous condition.
To prevent chafing, jamming, or other types of interference or
other failures that may lead to loss of control of the airplane, EWIS
in general and wiring in particular must be physically separated from
flight or other control cables. Mechanical cables have the potential to
cause chafing of electrical wire if the two come into contact. This can
occur either through vibration of the EWIS and/or mechanical cable or
because of cable movement in response to a system command. A mechanical
cable could also damage other EWIS components, such as a wire bundle
support, in a way that would cause failure of that component. Also, if
not properly designed and installed, a wire bundle or other EWIS
component could interfere with movement of a mechanical control cable
by causing jamming or otherwise restricting the cable's movement. An
arcing fault could damage or sever a control cable, or a control cable
failure could cause damage to EWIS if not adequately separated.
Therefore, proposed paragraph (i) would require an adequate separation
distance or barrier between EWIS and flight or other mechanical control
systems cables and their associated system components. It would further
require that failure of an EWIS component must not create a hazardous
condition and that the failure of any flight or other mechanical
control systems cables or systems components must not damage EWIS and
create a hazardous condition.
EWIS in general and wiring in particular must be routed away from
high-temperature equipment, hot air ducts, and hydraulic, fuel, water,
and other lines. There must be adequate separation distance in order to
prevent damage to the EWIS caused by extreme temperatures and so that
an EWIS failure will not damage the equipment, ducts, or lines. High
temperatures can deteriorate wire insulation and other parts of EWIS
components, and if the wire or component type is not carefully
selected, this deterioration could lead to wire or component failure.
Similarly, should an arcing event occur, the arc could penetrate a hot
air duct or line and allow the release of high pressure, high
temperature air. Such a release could damage surrounding components
associated with various airplane systems and potentially lead to a
hazardous situation. Paragraph (j) would require that EWIS be designed
and installed with an adequate separation distance or barrier between
the EWIS components and heated equipment, hot air ducts, and lines.
The needed reliability of some airplane systems, such as an
autoland system, requires that independent, redundant systems be used.
Loss of one channel of a redundant system would not decrease the
ability to continue safe operation. However, if both channels of a two-
channel system were lost because of a common failure, the results could
be catastrophic. To maintain the independence of redundant systems and
[[Page 58523]]
equipment so that safety functions required for safe operation are
maintained, adequate separation and electrical isolation between these
systems must be ensured. Paragraph (k) would require that EWIS
associated with any system that requires redundancy to meet
certification requirements be separated with an adequate separation
distance or barrier.
Paragraph (l) of proposed Sec. 25.1709 would require that EWIS be
designed and installed so they are adequately separated from aircraft
structure and protected from sharp edges and corners. The purpose of
this proposal is to minimize the potential for abrasion/chafing,
vibration damage, and other types of mechanical damage. Such protection
is necessary because over time the insulation on a wire that is
touching a rigid object, such as an equipment support bracket, will
fail and expose bare wire. This can potentially lead to arcing that
could destroy that wire and other wires in its bundle. Depending on the
amount of electrical energy being carried by the failed wire,
structural damage may also occur.
Section 25.1711 Component Identification: EWIS
Proposed Sec. 25.1711 would require applicants to identify EWIS
components using consistent methods that facilitate easy identification
of the component, its function, and its design limitations. For EWIS
associated with flight-essential functions, identification of the EWIS
separation requirement would also be required.
An important aspect of ensuring safe operation of airplanes is
making sure that EWIS components are properly identified. This is
necessary so that modification designers, maintenance personnel, and
inspectors can easily determine the function of the associated system,
together with any associated separation requirements and design
limitations. Clear labeling of EWIS components and easy-to-understand
identification aids allow installers, inspectors, and maintainers to
readily ascertain that correct system components are installed as
designed, and allow modifiers to add systems with due regard to the
existing protection and separation requirements.
The current part 25 certification requirement for equipment
identification is Sec. 25.1301(b) and it is applicable to ``each item
of installed equipment.'' This rule is inadequate for EWIS because it
does not provide the specific requirements that have been determined
necessary for identifying EWIS components. Specific EWIS component
identification needs to be done to prevent modifiers from
unintentionally introducing unsafe design or installation features on
previously certified airplanes when they install new or modified
systems. Component identification would also make those performing
maintenance and inspections more aware of what systems are associated
with specific EWIS in the areas undergoing maintenance or inspection.
When the FAA first certifies an airplane type design, its systems
are designed and installed to ensure safe operation of the airplane.
Systems essential to that safe operation are often designed and
installed to ensure redundancy of the system function. They have two or
more circuits, or channels, that can perform the same function in case
one of them malfunctions. Separate circuits (channels) typically have
their own sensors, wiring, and equipment. This helps ensure that a
common failure cannot cause failure of the entire system.
An example of this is the autoland system on modern transport
category airplanes. The autoland system allows airplanes to land during
adverse weather conditions that would otherwise prevent landing with
manual techniques that rely on the flightcrew's ability to see the
runway. Typically the autoland system has three channels that are
physically separated and electrically segregated, so if one channel
fails, the airplane can safely continue the autoland procedure. The
failure of an autoland system at a critical phase of flight can be
catastrophic to the airplane and its passengers. The integrity of an
autoland system's design could be compromised by systems installed
after certification of the autoland system. One way to prevent this is
to clearly identify EWIS associated with the autoland in a way that
makes it easy to see that it is associated with a critical system. Such
identification would aid the designers and installers of the new system
by alerting them to the presence of the critical system and allow
appropriate design and installation decisions, preventing degradation
of the safety of the autoland system.
The reverse is also true. For example, suppose an in-flight
entertainment system is installed on an airplane and, after that
installation, an autoland system is to be installed. The designers and
installers of the autoland system would need to be able to identify
EWIS associated with the IFE system so they do not mix IFE system EWIS
with the autoland system EWIS. The IFE system is a passenger
convenience item and its functionality is not important to the
continued safe operation of the airplane. When the zone containing the
autoland system EWIS is undergoing inspections or maintenance, easy
identification of the EWIS will alert inspection or maintenance
personnel to use extra caution in the area.
Proposed Sec. 25.1711(a) uses language that is similar to existing
Sec. 25.1301(b) but is specifically applicable to EWIS components. The
proposal adds the word ``consistent'' to stress the need for
consistency in EWIS identification to avoid confusion and mistakes
during airplane manufacturing, modification, and maintenance. This
means the FAA expects airplane manufacturers to develop an EWIS
identification method that facilitates easy identification of the
systems that any specific EWIS component supports and use that
identification method in a consistent manner throughout the airplane.
The consistent identification method must be used for new type
certifications and changes to those designs. Proposed Sec. 25.1711(e)
would require that modifications to type designs use EWIS
identification methods that are consistent with the identification
method of the original type design. The proposed requirements of
paragraph (e) are discussed later in this document.
Paragraph (b) would impose additional requirements for
identification detail, when assessed in accordance with the proposed
requirements of Sec. 25.1705, for EWIS components associated with:
Systems required for safe flight and landing.
Systems required for egress.
Systems with potential to affect the flightcrew's ability
to cope with adverse operating conditions.
Paragraph (c) would require that identifying markings required by
paragraphs (a) and (b) of the proposal remain legible throughout the
design life of the component. As most wire installations are designed
to remain on the airplane throughout the airplane's service life, this
means the identification marks must be able to be read to support the
intended purpose of the markings for the life of the airplane. The
method of marking must take into account the environment in which the
EWIS component will be installed.
Paragraph (d) would require that the means used to identify an EWIS
component does not have an adverse effect on the component's
performance throughout its design life. Certain wire marking methods
have the potential to damage the wire's insulation. Hot-stamp marking
is one such method. According to SAE (Society of Automotive Engineers)
aerospace information report
[[Page 58524]]
AIR5575, ``Hot Stamp Wire Marking Concerns for Aerospace Vehicle
Applications,'' a copy of which is included in the docket, the hot-
stamp marking method is not well suited for today's generation of
aircraft wiring. As noted in the SAE document, wire insulation has
become markedly thinner over the years since the procedure was first
introduced in the 1940s. Because of this, problems have arisen over
wire damage from excessive penetration by the hot-stamp process. The
document further states: ``The frequent need for adjustments in
temperature, pressure, and swell time inherent to achieving legible hot
stamp wire marking provides many opportunities for error. The controls,
methods, and guidance necessary to achieve satisfactory performance
with hot stamp marking are often not made available to operators in
smaller wire shops.''
The FAA concurs with this assessment. If damage to the insulation
occurs during the marking process, it may fail later in service after
it has been exposed to the sometimes-harsh environmental conditions of
aircraft use. While the proposed regulation does not prohibit use of
hot-stamp marking, its use is not encouraged. To comply with this
paragraph, if the hot stamp marking process is used, the guidelines of
SAE recommended practice ARP5369, ``Guidelines for Wire Identification
Marking Using the Hot Stamp Process'' or equivalent must be followed. A
copy of this document is in the docket.
In some cases it may not be practicable to mark an EWIS component
directly, because of component size or identification requirements. In
this case other methods of identification such as a label or sleeve
must be used.
Paragraph (e) would require that EWIS modifications to the type
design take into consideration the identification scheme of the
original type design. This is to ensure that the consistency required
by proposed Sec. 25.1711(a) is maintained when a modification is
installed. The intent of this requirement is to provide continuity in
the methods used for EWIS identification on a particular model. It is
not the intent of the requirement to impose on the modifier the exact
wire identification methods of the airplane manufacturer. However,
since the purpose of proposed Sec. 25.1711 is to make it easy to
identify those airplane systems essential to the safe operation of the
airplane, it is in the best interest of safety that designers of any
modifications to the original design consider the approved type design
identification methods. For example it would not be appropriate for a
modifier to use purple wire to identify a specific flight critical
system when the approved type design used the color green, especially
if the type design already uses purple wire to identify non-essential
systems. Such a scheme could cause confusion and lead future modifiers
or maintainers to believe that the routing of purple wires with green
wires is acceptable. This is just an example and should not be
construed to say that flight critical systems should use green wire or
non-essential systems purple wire. The regulation does not prescribe a
particular method for identification, but is meant to ensure that the
consistency of the identification method required by paragraph (a) is
maintained throughout the life of the airplane.
Section 25.1713 Fire Protection: EWIS
Proposed Sec. 25.1713 would require that EWIS components meet the
applicable fire and smoke protection requirements of Sec. 25.831(c).
It would further require that EWIS located in designated fire zones be
at least fire resistant. Insulation on electrical wires and cables
would also be required to be self-extinguishing when tested in
accordance with the applicable portions of Appendix F, Part I, of part
25.
During an emergency situation it is important that airplane systems
needed by the flightcrew to effectively deal with the emergency be
operative. To help ensure this, Sec. 25.869 requires that electrical
systems components meet certain flammability requirements and be
designed and installed to minimize probability of ignition of flammable
fluids and vapors. Currently, Sec. 25.869(a) is applicable to wiring.
The proposal is to move the requirements of Sec. 25.869(a) related to
protection of wiring from fire and put them into the proposed Sec.
25.1713. This will allow easy identification of the requirements for
fire protection of EWIS, because they will be found in the proposed new
subpart H, which is dedicated to EWIS regulations. Requirements of
Sec. 25.869 dealing with isolation from flammable fluid lines have
been moved to the new Sec. 25.1709 and requirements for allowance for
deformation and stretching have been moved to Sec. 25.1703. As a
result, we are amending Sec. 25.869 to accommodate this change.
Section 25.1717 Electrical Bonding and Protection Against Static
Electricity: EWIS
Proposed Sec. 25.1717(a) would require that EWIS used for
electrical bonding and protection against static electricity meet the
requirements of Sec. 25.899. Proposed Sec. 25.1717(b) would require
that EWIS components used for any electrical bonding purposes (not just
that used for protection against static electricity) provide an
adequate electrical return path under both normal and fault conditions.
The buildup and subsequent discharge of static electricity has the
potential to create hazardous conditions for both airplane systems and
people. Static electricity can injure people. It can also interfere
with installed electrical/electronic equipment and cause ignition of
flammable vapors. We are proposing to adopt Sec. 25.899 (as discussed
in the section headed ``Electrical System Harmonization Rules'') to
highlight the importance of considering electrical bonding and static
electricity as a full aircraft requirement and to prevent hazardous
effects of static electricity. The proper design and installation of
EWIS components used to accomplish such protection is critical to
ensure the hazardous effects of static discharge are minimized. For
example, the cross-sectional area of bonding paths used for primary
bonding paths is important in ensuring that a low electrical impedance
is obtained, as is the method in which the bonding connection is made
to the airplane structure. Thus, EWIS must be fully considered when
designing and installing protection from the adverse effects of static
electricity. The proposed Sec. 25.1717 highlights the importance EWIS
has in providing this protection and requires that EWIS components meet
the same requirements as other components used to show compliance with
Sec. 25.899.
The ARAC Electrical Systems Harmonization Working Group recommended
the adoption of JAR 25.1353(e) as paragraph (e) of Sec. 25.1353. The
JAR requires that electrical bonding provide an adequate electrical
return path under both normal and fault conditions on airplanes with
grounded electrical systems. ATSRAC recommended that the requirements
of JAR 25.1353(e) be moved in their entirety to the proposed subpart H.
We agree with that recommendation and, instead of adopting JAR
25.1353(e) as Sec. 25.1353(e), we are proposing to adopt it as Sec.
25.1717(b).
Section 25.1719 Systems and Functions: EWIS
Proposed Sec. 25.1719 would require that EWIS components be
considered in showing compliance with the certification requirements of
specific airplane systems. Many of the current part 25 sections contain
system specific requirements that apply to EWIS in an
[[Page 58525]]
indirect way. The EWIS associated with such systems play an integral
role in ensuring the safe operation of the system and of the airplane.
In general, the EWIS associated with any airplane system needs to be
considered an integral part of that system and must be given the same
design and installation attention as the rest of the system. The
proposed Sec. 25.1719(a) contains this general requirement, while
paragraph (b) of the proposal identifies specific sections of part 25
that are associated with airplane systems where wire and its associated
components play an important part in ensuring safety. These specific
part 25 sections contain requirements that do not lend themselves to
creating a separate EWIS-based Subpart H requirement.
It is the intent of the proposed Sec. 25.1719 to require that EWIS
be designed and installed to support systems required for type
certification or by operating rules, including those systems addressed
by the regulations specifically listed in paragraph (b) of the
proposal. They must be considered part of those systems, and be given
the same design and installation considerations as the rest of the
system. While paragraphs (a) and (b) may seem redundant, we have listed
specific sections in (b) to ensure that applicants are aware of the
need to give EWIS associated with those systems the same consideration
as the other components of those systems. We consider the general
requirements of (a) necessary because there may be other regulations
where EWIS must be considered in showing compliance with those
regulations. It also ensures that EWIS is given full consideration for
any system-related regulation adopted in the future.
Section 25.1721 Circuit Protective Devices: EWIS
Proposed Sec. 25.1721 would require that electrical wires and
cable be compatible with the circuit protective devices required by
Sec. 25.1357.
We recently adopted Sec. 25.1353(d)(1) based on recommendations of
ARAC, as part of the effort to harmonize the requirements of JAA JAR 25
and FAA 14 CFR part 25. Paragraph (d)(1) requires that electrical
cables be compatible with the circuit protection devices required by
Sec. 25.1357, so that a fire or smoke hazard cannot be created under
temporary or continuous fault conditions. That requirement would be
moved from Sec. 25.1353(d)(1) into the proposed Sec. 25.1721 in its
entirety. The proposal also adds the word ``wire'' to the requirement.
This is because this requirement applies to all sizes of wire, not just
heavy-current-carrying cables.
Section 25.1723 Instruments Using a Power Supply: EWIS
The proposed Sec. 25.1723 would require that EWIS components
associated with flight and navigation instruments using a power supply
be designed and installed so that compliance with Sec. 25.1331 is
ensured.
Section 25.1331 requires that flight and navigation instruments
using a power supply must, in the event of the failure of one power
source, be supplied by another power source. No change is proposed to
the wording of that section.
Section 25.1725 Accessibility Provisions: EWIS
The proposed new Sec. 25.1725 would require that means be provided
to allow for inspection of EWIS and replacement of their components as
necessary for continued airworthiness.
Currently, Sec. 25.611 requires that means must be provided to
allow inspection, replacement of parts, adjustment, and lubrication as
necessary for principal structural elements and control systems. While
wiring systems are not specifically referred to in the existing rule,
the ``accessibility'' concept is easily applied to EWIS. Many of the
wiring systems on airplanes today are very difficult to access and
inspect. We now have an increased awareness of the importance of
inspecting wiring for separation and for contamination and damage in
order to ensure proper functioning, maintenance, and safety. We also
know that when adjacent structures must be removed to allow access to
wire installations, new possibilities for contamination, chafing, and
other types of damage are introduced. Section 25.611 would be amended
to specify that EWIS must meet the accessibility requirements of Sec.
25.1725.
The intent of proposed Sec. 25.1725 is to ensure that EWIS
components be installed so that inspections, tests, repairs, and
replacements can be undertaken, and that these can be carried out with
a minimum of aircraft disassembly. This proposal would facilitate the
proposed implementation of the new wiring inspection programs developed
under proposed Sec. 25.1739 and the operating rules contained in this
proposal.
Section 25.1727 Protection of EWIS
Proposed Sec. 25.1727 would require that cargo or baggage
compartments not contain any EWIS whose failure would adversely affect
safe operation. It would also require that all EWIS be protected from
damage by movement of people.
Section 25.855(e) requires that no cargo or baggage compartments
may contain any controls, wiring, lines, equipment, or accessories
whose damage or failure would affect safe operation of the airplane
unless they are protected so that they cannot be damaged by movement of
cargo in the compartment and their breakage or failure will not create
a fire hazard. The proposed regulations would remove the word
``wiring'' from the current language and move those requirements, as
they apply to EWIS, to the proposed Sec. 25.1727(a). Proposed Sec.
25.855(j) would mandate that cargo or baggage compartment EWIS
components must meet the requirements of Sec. 25.1727(a).
The proposed Sec. 25.1727(b) and (c) are new EWIS requirements
that currently don't exist in part 25. Paragraph (b) would require that
EWIS be designed so that damage and risk of damage from movement of
people in the airplane during all phases of flight, maintenance, and
service, be minimized. Paragraph (c) would require designers to
minimize damage and risk of damage to EWIS by items carried onto the
airplane by passengers, cabin crew, and flightcrew. These two new
requirements are justified by service experience that shows wires can
easily be damaged by movement of people on the airplane and by items
carried on board.
Paragraph (b) would require that EWIS designers and installers
consider such things as the routing of wires that could be damaged by
personnel in the cargo compartments. For example, EWIS would have to be
designed and installed in ways that prevent their use as hand-or
footholds as much as practicable. It would further require that EWIS be
protected from damage by people in the cabin or flight deck. More and
more wiring is being routed to passenger seats to support increasingly
complex passenger convenience features. If an airplane is equipped with
seat-back monitors, for example, the electronic components necessary to
support the monitor are typically mounted underneath the seat. This
requires wire routing to the seats, usually through the seat tracks
(structural channels used to fasten the seats to the floor) or from the
side wall directly next to the seat. Many wires mounted on or under the
seats have been damaged by passengers. In one case an airplane was
operated with wires lying on the floor in the area where a passenger
would put his feet. The wires had become dislodged from the seat track.
This not only exposed the wires to damage but also posed a potential
electrical shock risk to the passenger. In other cases, wires have been
routed to the seats through holes cut into the cabin side wall,
exposing them to damage from both passengers
[[Page 58526]]
and carry-on items stored beneath the seat or between the side wall and
seat.
Section 25.1729 Flammable Fluid Fire Protection: EWIS
The proposed Sec. 25.1729 would require that EWIS components be
considered a potential ignition source in each area where flammable
fluid or vapors might escape by leakage of a fluid system and must meet
the requirements of Sec. 25.863.
The current Sec. 25.863 mandates that, in each area where
flammable fluids or vapors might escape by leakage of a fluid system,
there must be means to minimize the probability of ignition, and
resultant hazards if ignition does occur. Possible ignition sources,
including overheating of equipment, malfunctioning of protective
devices, and electrical faults must be considered in showing compliance
with this rule. Many types of electrical faults could cause ignition.
Among them are sparks emitting from an avionics component, overheated
electrical component surfaces, and arcing from electrical wiring. The
wording of Sec. 25.863 would not change.
Section 25.1731 Powerplants: EWIS
The proposed Sec. 25.1731 specifies that EWIS associated with any
powerplant must be designed and installed so that failure of an EWIS
component will not prevent continued safe operation of the remaining
powerplants or require immediate action by any crewmember for continued
safe operation, in accordance with Sec. 25.903(b). It would also
mandate that design precautions be taken to minimize hazards to the
airplane because of EWIS damage in the event of a powerplant rotor
failure or a fire originating in the powerplant that burns through the
powerplant case, in accordance with Sec. 25.903(d)(1). The purpose of
this section is to ensure proper consideration of EWIS in evaluating
powerplant installation designs.
The current Sec. 25.903(b) requires, among other things, that
powerplants be arranged and isolated from each other to allow
operation, in at least one configuration, so that failure or
malfunction of any engine, or of any system that can affect the engine,
will not prevent continued safe operation of the remaining engines or
require immediate action by any crewmember for continued safe
operation. Section 25.901(d)(1) requires that design precautions be
taken to minimize hazards to the airplane in the event of an engine
rotor failure or a fire originating within the engine that burns
through the engine case.
Section 25.1733 Flammable Fluid Shutoff Means: EWIS
Proposed Sec. 25.1733 would require that EWIS associated with each
flammable fluid shutoff means and control be ``fireproof'' (as defined
in Sec. 1.1) or located and protected so that any fire in a fire zone
will not affect operation of the flammable fluid shutoff means, in
accordance with Sec. 25.1189.
Section 25.1189 requires that each engine installation and fire
zone have a means to shut off or otherwise prevent hazardous quantities
of fuel, oil, deicer, and other flammable fluids from flowing into or
through any designated fire zone. No change is proposed for that
section.
Section 25.1735 Fire Detector Systems, General: EWIS
Proposed Sec. 25.1735 would require that EWIS associated with any
installed fire protection system be considered in showing compliance
with the applicable requirements for that particular system. This would
be a new requirement. It does not currently exist in part 25. The
current part 25 regulations contain fire detection system requirements
for powerplants (Sec. 25.1203), lavatories (Sec. 25.854), and cargo
compartments (Sec. Sec. 25.855, 25.857 and 25.858). Each fire
detection system requires electrical wire. Failure of this wire could
lead to inability of the detection system to function properly. The
wire and other associated EWIS components must be considered an
integral part of the fire detection system and meet the requirements of
the applicable regulation. The proposal would apply to all required
fire protection systems with the exception of powerplants and APUs.
Requirements for EWIS associated with powerplant and APU fire detection
systems are contained in proposed Sec. 25.1737.
Section 25.1737 Powerplant and APU Fire Detector System: EWIS
Proposed Sec. 25.1737 would require that EWIS that are part of a
fire or overheat detector system located in a fire zone be at least
fire-resistant, as defined in Sec. 1.1. It would also require that
EWIS components of any fire or overheat detector system for any fire
zone may not pass through another fire zone unless:
They are protected against the possibility of false
warning caused by fire in the zone through which they pass, or
Each zone involved is simultaneously protected by the same
detector or extinguishing system.
In addition, the proposal would require that EWIS that are part of
a fire or overheat detector system in a fire zone meet the requirements
of Sec. 25.1203.
The current Sec. 25.1203 requires approved, quick acting fire or
overheat detectors in each designated fire zone, and in the combustion,
turbine, and tailpipe sections of turbine engine installations, to
provide prompt indication of fire in those zones. The present rule does
contain requirements for wire used in the fire detection systems. But
to increase visibility of the related EWIS requirements and to gather
them into one central place, a new rule devoted specifically to fire
detector system EWIS is proposed.
Existing Sec. 25.1203 would be amended to reference the new Sec.
25.1737, thus effectively closing the loop on requirements.
Section 25.1739 Instructions for Continued Airworthiness: EWIS
Proposed Sec. 25.1739 would require that applicants prepare EWIS
ICA in accordance with the requirements of Appendix H to part 25. The
proposed EWIS ICA requirements are discussed in the next section of
this document.
B. Part 25 Subpart I--Continued Airworthiness and Related Part 25
Changes
As discussed below, the following proposals are applicable to
holders of existing TCs for transport category airplanes and applicants
for approval of design changes to those certificates. On July 12, 2005,
we issued policy statement PS-ANM110-7-12-2005, ``Safety--A Shared
Responsibility--New Direction for Addressing Airworthiness Issues for
Transport Airplanes'' (70 FR 40166). The policy states, in part,
``Based on our evaluation of more effective regulatory approaches for
certain types of safety initiatives and the comments received from the
Aging Airplane Program Update (July 30, 2004), the FAA has concluded
that we need to adopt a regulatory approach recognizing the shared
responsibility between design approval holders (DAH) and operators.
When we decide that general rulemaking is needed to address an
airworthiness issue, and believe the safety objective can only be fully
achieved if the DAHs provide operators with the necessary information
in a timely manner, we will propose requirements for the affected DAHs
to provide that information by a certain date.''
We believe that the safety objectives contained in this proposal
can only be reliably achieved and acceptable to the FAA if the DAHs
provide the operators with the EWIS- and fuel-tank-system-
[[Page 58527]]
related maintenance information required by the proposed operational
rules for parts 91, 121, 125, and 129. Our determination that DAH
requirements are necessary to support the initiatives contained in this
proposal is based on several factors:
Developing EWIS and fuel tank system ICA is complex. Only
the airplane manufacturer, or DAH, has access to all the necessary type
design data needed for the timely and efficient development of the
required EWIS and fuel tank system maintenance tasks.
FAA-approved EWIS and fuel tank system ICA need to be
available in a timely manner. Due to the complexity of these ICA, we
need to ensure that the DAHs submit them for approval on schedule. This
will allow the FAA Oversight Office having approval authority to ensure
that the ICA are acceptable, are available on time, and can be readily
implemented by the affected operators. Additionally, accurate and
timely information is necessary to ensure alignment with the
requirements of the Fuel Tank Safety Rule (FTSR). The compliance
deadline for the operational requirements of the FTSR was extended to
facilitate this alignment, as stated in the Federal Register notice ``
Fuel Tank Safety Compliance Extension (Final Rule) and Aging Airplane
Program Update (Request for Comments)'' (69 FR 45936).
The proposals in this NPRM affect a large number of
different types of transport airplanes. Because the safety issues
addressed by this proposal are common to many airplanes, we need to
ensure that technical requirements are met consistently and the
processes of compliance are consistent. This will ensure that the
proposed safety enhancements are implemented in a standardized manner.
The safety objectives of this proposal need to be
maintained for the operational life of the airplane. We need to ensure
that future design changes to the type design of the airplane do not
degrade the safety enhancements achieved by the initial incorporation
of EWIS and fuel tank system ICA. We need to be aware of future changes
to the type designs to ensure that these changes do not invalidate the
maintenance tasks assigned to a particular type design when the ICA are
first developed under the requirements of this proposal.
Based on the above reasons and the stated safety objectives of FAA
policy PS-ANM110-7-12-2005, we are proposing to implement DAH
requirements applicable to EWIS and fuel tank system ICA.
In the past, we have issued a similar requirement in the form of a
special federal aviation regulation (SFAR). But SFARs appear in various
places in the CFR and are difficult to reference as a whole. The FAA
believes that placing these types of requirements in a new subpart of
part 25, which contains the airworthiness standards for transport
category airplanes, would provide a single, readily accessible location
for this type of requirement. Therefore, we are proposing new subpart I
to part 25 to contain these requirements.
In preliminary discussions with foreign airworthiness authorities
of the concept of this new subpart, they have expressed concerns that
their regulatory systems may not be able to accommodate these types of
requirements in their counterparts to part 25. While agreeing on the
need for these types of requirements, they have suggested that it may
be more appropriate to place them in part 21 or another location. As
discussed below, because we expect these new subpart I requirements to
be similar to new part 25 airworthiness standards, we have tentatively
decided to place them in part 25. However, we specifically request
comments on the appropriate location of these requirements,
particularly from the foreign authorities. If, based on comments
received, we conclude that another location is more appropriate, we may
move them in the final rule. Because such a move would not affect the
substance of the requirements themselves, we would not consider this to
be an expansion of the scope of this rulemaking that would require
additional notice and comment procedures.
Section 25.1 Applicability
As stated in Sec. 25.1, part 25 currently prescribes airworthiness
standards for issuance of TCs, and changes to those certificates, for
transport category airplanes. As discussed in more detail above, with
this NPRM the FAA is proposing to expand the coverage of part 25 to
include a new subpart I containing requirements that must be complied
with by current holders of these certificates. Therefore, we are
proposing to amend Sec. 25.1, ``Applicability,'' to state that part 25
also includes requirements for holders of these design certificates. As
discussed in the FAA's final rule, ``Fuel Tank Safety Compliance
Extension and Aging Airplane Program Update'' (69 FR 45936), this NPRM
is one of several proposals for adoption of these kinds of requirements
for current holders of type certificates.
A theme common to this and other possible subpart I proposed rules
is that the rulemaking projects include proposals for changes to
operational rules to require operators to implement programs or take
other actions that the FAA has determined are necessary for safety. In
several recent rules we have adopted operational requirements without a
corresponding requirement for design approval holders to develop and
provide the necessary data and documents to support the operators'
compliance. The difficulty encountered by operators in complying with
these rules has convinced us that the corresponding design approval
holder requirements are necessary to enable operators to comply by the
regulatory deadlines.
Section 25.2 Special Retroactive Requirements
Section 25.2 currently contains ``special retroactive
requirements.'' These requirements are ``retroactive'' in the sense
that they require applicants for changes to TCs to comply with
requirements that were not applicable to the original TC. As discussed
below, proposed subpart I would have a similar effect, in that it would
impose new requirements on both existing design certificate holders and
applicants for changes to those certificates. Therefore, we are
proposing to amend Sec. 25.2 to make reference to proposed subpart I.
Section 25.1801 Purpose and Definition
Paragraph (a) of this section states that this subpart would
establish requirements for holders of TCs to take actions necessary to
address particular safety concerns or to support the continued
airworthiness of transport category airplanes. Such actions may
include, but are not limited to, performing assessments, making design
changes, developing revisions to ICA, and making necessary
documentation available to affected persons.
The specific applicability of each subpart I rule will be
established as part of the rulemaking adopting each rule. Generally
this subpart would also apply to applicants for type certificates and
changes that are pending as of the effective date of this rule. It
would also apply to future applicants for changes to existing type
certificates. Under Sec. 21.101, the FAA may determine that it is not
appropriate to require such applicants to comply with new airworthiness
standards, such as proposed new subpart H. However, it is appropriate
for them to comply with the same requirements as existing certificate
holders. Otherwise, the safety
[[Page 58528]]
improvements that result from type certificate holder compliance with
these requirements could be undone by later modifications.
For example, in the case of this proposed rule, as discussed below,
operators would be required to revise their maintenance programs based
on EWIS ICA developed by the type certificate holder. Unless future STC
applicants are required to provide similar ICA for their modifications,
the TC holder's ICA could become obsolete or, in some cases, even
provide incorrect and potentially unsafe information as applied to the
STC holder's modification. In other cases, because subpart I rules
accompany corresponding operating requirements, failure of an STC
applicant to comply with a subpart I rule could make it impossible for
an operator to comply with the corresponding operating requirement.
Subpart I does not apply to future applicants for TCs, because those
applicants will be covered by other proposed changes to part 25,
including Appendix H.
Therefore, adoption of a new subpart I rule would also necessitate
new requirements for certification of changes to TCs that are in
addition to the requirements that are specified under Sec. 21.101.
Under that section, if a change is ``significant'' and certain other
criteria are met, the applicant would have to show compliance with the
latest airworthiness requirements. For example, an applicant applying
for such a change after this final rule becomes effective would have to
comply with the proposed EWIS requirements in subpart H. Even if we
determine that these broader regulations do not apply, the applicant
for a change must still comply with the subpart I rule.
Paragraph (b) of this section provides a definition of the term
``FAA Oversight Office.'' The FAA Oversight Office is the aircraft
certification office or office of the Transport Airplane Directorate
with oversight responsibility for the relevant TC or STC, as determined
by the Administrator. As stated later in the discussion of the proposed
operating rules, the primary means for operators to comply with those
requirements would be by implementing programs or taking other actions
developed by the TC and STC holders under this proposed subpart. In
each case, to ensure compliance with the relevant subpart I rule, the
TC and STC holder's compliance documentation (for example, in this
case, EWIS ICA) must be submitted to the FAA Oversight Office. Because
we expect this will be a standard approach to compliance with the
requirements of this subpart, we are including this definition in this
section to avoid having to repeat it in each section within this
subpart.
Section 25.1805 Electrical Wiring Interconnection Systems (EWIS)
Maintenance Program
This proposal would apply to holders of TCs and to applicants for
new TCs, amended TCs, and supplemental TCs if the application was filed
before the effective date of this rule and the certificate was issued
on or after the effective date of this rule. It would also apply to
future applicants for approval of changes to existing TCs.
Paragraph (a) states that this rule would apply, with some
exceptions, to transport category turbine-powered airplanes with a
maximum type-certificated capacity of 30 or more passengers, or a
maximum payload capacity of 7500 pounds or more resulting from the
original certification of the airplane or later increase in capacity.
This would result in the coverage of airplanes where the safety
benefits and the public interest are the greatest.
The reference to the originally certificated capacity, or later
increase in capacity, is intended to address two situations:
In the past, some designers and operators have tried to
avoid applying requirements mandated only for airplanes over specified
capacities by getting a design change approval for a slightly lower
capacity. By referencing the capacity resulting from original
certification, this proposal would remove this possible means of
avoiding compliance.
It is also possible that an airplane design could be
originally certified with a capacity slightly lower than the minimum
specified in this section, but through later design changes, the
capacity could be increased above this minimum. The reference to later
increases in capacity would ensure that, if this occurs, the design
would have to meet the requirements of this section.
Compliance is not proposed for airplanes with a certificated
passenger capacity of fewer than 30 passengers, or having a maximum
capacity of less than 7500 pounds payload resulting from original
certification, because it is not clear at this time that the possible
benefits for those airplanes would be proportionate to the cost
involved. The FAA intends to evaluate the merits of applying these
requirements to those airplanes. We are currently working with ATSRAC
to assess how these issues might be addressed in those transport
category airplanes. We request comments on the feasibility and benefits
of requiring holders of TCs for those airplanes to comply with these
requirements.
This proposed rule, as it applies to EWIS, is not applicable to
holders of existing (already issued) STCs. Often, the wire design for
STC installations of EWIS was based on operator or repair station
standard practices and therefore details of the installation are not
available. In the cases where such information is available, it would
usually indicate that the wiring for the modification follows the same
path, or is in the same airplane zone, as the wiring in the original
type design. We anticipate that operators would inspect those areas
while performing the TC holder's EZAP program. We also expect that any
possible discrepancies will be further mitigated by operators
incorporating applicable EWIS maintenance tasks into the maintenance
program for that zone. Accordingly, the FAA has decided not to require
compliance with this section for existing STCs. However, if an existing
STC is amended, this section would apply to the amendment.
TC holders, who design EWIS on airplanes, are the technical experts
who possess information about those systems. This proposal would apply
to the following:
TC holders.
Applicants for TCs and for approval of design changes to
existing TCs whose applications are pending when this rule becomes
effective.
Future applicants for approval of design changes to
existing TCs.
Section 25.1805(b) would require TC holders to complete a
comprehensive assessment of the EWIS of each ``representative''
airplane for which they hold a TC, develop inspection and maintenance
instructions for them, and incorporate those instructions into the
airplane's ICA. The ``representative'' airplane is defined as the
configuration of each model series airplane that incorporates all the
variations of EWIS used on that model, and that includes all TC-holder-
designed modifications mandated by AD, as of the effective date of this
rule.
For example, for the Boeing Model 737, the representative airplane
would be the configuration of each of the airplane series, 737-100
through 737-900 that incorporates all the variations of EWIS used in
producing each airplane series. The purpose of this definition is to
ensure that the TC holder considers the full range of EWIS
configurations that may affect the results of the EZAP. Further, AD 99-
03-04 applies to all Boeing Model 737-100, -200, -300, -400, and -500
series
[[Page 58529]]
airplanes. It requires installation of components to provide shielding
and separation of the fuel system wiring from adjacent wiring. It also
requires installation of flame arrestors and pressure relief valves in
the fuel vent system. Boeing would be required to develop ICA for each
of those series airplanes as modified by installation of these
components and all other modifications mandated by ADs.
The purpose of including these mandated design changes is to ensure
that the TC holder's EZAP addresses the existing configuration of
airplanes in the operating fleet, rather than just the configuration
produced and delivered by the manufacturer.
Applicants for approval of design changes would be required to
evaluate the effect of their proposed change on the EWIS ICA developed
by the TC holder for the representative airplane and to develop EWIS
ICA to address those effects. For TC holders, this requirement would
apply to any design changes that may affect the ICA for the
representative airplane. This includes service bulletins describing
such design changes. Under Sec. 21.113, these design changes are
amendments to the TC.
A description of what must be included in those ICA, and the EZAP
that must be used to develop them, is contained in the section of this
preamble discussing the proposed revision to Appendix H, part 25.
The requirement for ICA was effective on January 28, 1981. TC
holders whose application was dated before that date are not subject to
that requirement. This proposal would require TC holders who do not
have ICA for specific airplane models to create EWIS ICA for them. As
discussed below, air carriers and operators of those airplanes would
then be required to revise their maintenance or inspection programs
based on the new ICA for EWIS and fuel tank systems.
As discussed earlier, SFAR 88 requires TC holders to develop
maintenance and inspection instructions to assure the safety of the
fuel tank system. Proposed Sec. 25.1805(b) would require that TC
holders align the fuel tank system instructions with the results of the
EZAP applied to EWIS to ensure compatibility and minimize redundancies.
All EWIS would be subject to review in developing the EWIS ICA, and the
appropriate instructions for their maintenance and inspection would be
required. But some EWIS are also part of the fuel tank system. The
requirements for their maintenance and inspection might be more
specific than those for wiring in general, and might contain additional
requirements. That is why the two must be reviewed for compatibility.
As discussed later in this section, the ICA for fuel tank system
electrical wiring required by SFAR 88 will be determined in accordance
with guidance provided by Policy Statement ANM100-2004-1129, ``Process
for Developing Instructions for Maintenance and Inspection of Fuel Tank
Systems Required by SFAR 88'' (a copy of which may be found in the
docket), or other acceptable process. Compliance with Subpart I will
require ICA for the same wire to be determined using an EZAP. While
these processes have similarities, they may result in identification of
different tasks and intervals. The ICA maintenance tasks and intervals
that result from these determinations are expected to be additive. If
there is a conflict in the task or interval, for purposes of this
section, the FAA Oversight Office will resolve the conflict.
The ICA should be reviewed to ensure that any maintenance tasks for
EWIS do not compromise fuel tank system wire requirements, such as
separation or configuration specifications. If there is an inspection
or maintenance requirement for EWIS and the fuel tank system within the
same zone, there must be an effort to align the task interval. In
addition, design certificate holder's existing documents containing
EWIS and fuel tank system ICA should be reviewed to either remove or
cross-reference redundant information.
The compliance plan required by this proposal must include
identification of those common locations in the airplane where EWIS and
fuel tank ICA apply. The considerations for compatibility and
minimization of redundancy for the two systems will be reviewed and
approved by the FAA Oversight Office. The plan for documenting the
required ICA for EWIS and fuel tank system will also be reviewed as
part of the compliance plan. These documents are critical to the effort
that will be required of operators to show compliance with the
operational rules contained in this proposal. We intend that the ICA
information, both in content and format, will be readily usable by the
affected operators for developing proposed changes to their maintenance
or inspection programs. Generally, the information contained in the ICA
for the fuel tank system required by SFAR 88 would include:
The location of the fuel tank system components to be
maintained or inspected and any access requirements.
Any unique procedures required, such as special, detailed
inspections or dual sign-off of maintenance records.
Specific task information, such as inspections defined by
pictures or schematics.
Intervals for any repetitive tasks.
Methods, techniques, and practices required to perform the
task.
Criteria for passing inspections.
Any special equipment or test apparatus required.
Critical Design Configuration Control Limitations--for
example, wire separation or pump impeller material specifications--that
cannot be altered, except in accordance with the applicable limitation.
The information for EWIS ICA would generally include:
Identification of each zone of the airplane.
Identification of each zone that contains EWIS.
Identification of each zone containing EWIS that also
contains combustible material.
Identification of each zone in which EWIS is in close
proximity to both primary and back-up hydraulic, mechanical, or
electrical flight controls and lines.
The location of the EWIS components to be maintained or
inspected and any access requirements.
Any unique procedures required, such as special, detailed
inspections, or a dual sign-off of maintenance records.
Specific task information, such as inspections defined by
pictures or schematics.
Intervals for any repetitive tasks.
Methods, techniques and practices required to perform the
task.
Criteria for passing inspections.
Any special equipment or test apparatus required.
Instructions for protection and caution information that
will minimize contamination and accidental damage to EWIS during
performance of maintenance, alterations, or repairs.
Guidelines for identifying wiring discrepancies and
assessing what effect such discrepancies, if found, could have on
adjacent systems, particularly if these include wiring.
Critical Design Configuration Control Limitations--for
example, wire separation specifications--that cannot be altered, except
in accordance with the applicable limitation.
Policy Statement No. PS-ANM100-2004-10029 provides guidance on
acceptable processes for developing fuel tank system ICA as required by
SFAR 88. The FAA expects that engineers from aircraft certification
offices or from the Transport Airplane Directorate will review and
approve the results of the EZAP.
The three groups whose compliance with this proposal would be
required,
[[Page 58530]]
and their required compliance dates, indicated in paragraph (c), are as
follows:
Existing TC holders: No later than December 16, 2007.
Current applicants for TCs and amendments to TCs
(including service bulletins describing design changes) whose
applications are pending and future applicants for TC amendments: No
later than December 16, 2007, or the date of approval of their
application, whichever is later.
Pending and future applicants for STCs: No later than June
16, 2008, or the date of the approval of their application, whichever
is later.
Future applicants for changes to TCs that comply with proposed
Sec. 25.1739 would not be required to comply with this section. As
discussed previously, under Sec. 21.101, applicants for
``significant'' changes that meet certain criteria must comply with the
latest airworthiness requirements. If this NPRM is adopted as a final
rule, such a future applicant would have to comply with Sec. 25.1739.
Because the proposed requirements of that section are more extensive
than the proposed requirements of Sec. 25.1805, requiring compliance
with this section would be redundant.
In determining the compliance schedules for the requirements
covered in this proposal, the FAA balanced the safety-related reasons
for the rule against the need to give industry enough time to comply
with it. Therefore, before setting the proposed compliance times for
the TC holders to complete their analysis of their representative type
design, the FAA considered the following:
Input from industry.
Current or planned compliance periods of several aging-
related rulemakings, such as the pending Aging Airplane Safety proposed
rule, Fuel Tank System safety initiatives (69 FR 45936, 66 FR 23086),
and the pending Widespread Fatigue Damage proposal.
Safety improvements that will result from compliance with
this rule.
Industry's current efforts to incorporate some of these
safety initiatives.
ATSRAC recommended a compliance time of 24 months for TC holders to
develop these ICA. To align this proposal with other rules in the aging
airplane program, the FAA has adjusted the time frame to that of other
rules discussed earlier, so that operators can more efficiently comply
with requirements to revise their maintenance programs. To support this
realignment, compliance dates that allow an 18-month time frame for TC
holders to develop the EWIS ICA and 12 months for operators to
implement them were determined to be appropriate and were included in
this proposal. We believe these time frames are supported by the
experience gained from the EZAPs already performed. Since ATSRAC made
its recommendation, several manufacturers have applied an EZAP to their
type design airplanes and have completed those reviews.
When we initially drafted this proposal, we assumed the final rule
would be adopted by mid-2006. As a result, we set the compliance dates
in the proposal using the mid-2006 time frame as the baseline. However,
the proposed rulemaking process took longer than we had anticipated.
Consequently, we expect that the time frame for adoption of the final
rule will be sometime after mid-2006. We recognize that this delay will
adversely impact the compliance dates we propose for TC holders and
operators and we may need to adjust them. Therefore, we request and
will consider your comments on revising the proposed compliance dates.
Once the ICA are approved by the FAA Oversight Office, the submitter
must make the ICA available to affected persons as required by Sec.
21.50.
Because this proposal sets a precedent in introducing part 25
requirements for holders of existing TCs, it is the FAA's expectation
that they will work closely with the FAA Oversight Office in putting
together a compliance plan for developing the required ICA. Proposed
section 25.1805(d) would require that the compliance plan be approved
by the FAA Oversight Office as sufficient basis for showing compliance
with the proposed Sec. 25.1805.
The following table lists the FAA Oversight Offices, as currently
determined by the Administrator, that oversee issuance of type
certificates and amended type certificates for manufacturers of
transport category airplanes with a passenger capacity of 30 passengers
or a payload capacity of 7500 pounds or greater.
------------------------------------------------------------------------
Airplane manufacturer FAA Oversight Office
------------------------------------------------------------------------
Aerospatiale........................... Transport Airplane Directorate,
International Branch, ANM-116.
Airbus................................. Transport Airplane Directorate,
International Branch, ANM-116.
BAE.................................... Transport Airplane Directorate,
International Branch, ANM-116.
Boeing................................. Seattle Aircraft Certification
Office.
Bombardier............................. New York Aircraft Certification
Office.
CASA................................... Transport Airplane Directorate,
International Branch, ANM-116.
deHavilland............................ New York Aircraft Certification
Office.
Dornier................................ Transport Airplane Directorate,
International Branch, ANM-116.
Embraer................................ Transport Airplane Directorate,
International Branch, ANM-116.
Fokker................................. Transport Airplane Directorate,
International Branch, ANM-116.
Lockheed............................... Atlanta Aircraft Certification
Office.
McDonnell-Douglas...................... Los Angeles Certification
Office.
SAAB................................... Transport Airplane Directorate,
International Branch, ANM-116.
------------------------------------------------------------------------
Development of a compliance plan is necessary to ensure that TC
holders thoroughly understand the requirements of this proposal and
produce on time appropriate ICA that are acceptable in content and
format in addressing the maintenance and inspection tasks for EWIS and
the fuel tank system. Integral to the compliance plan will be the
inclusion of procedures to allow the FAA to monitor progress towards
compliance. These aspects of the plan will help ensure that the
expected outcomes will be acceptable and on time for incorporation by
the affected operators in accordance with the operational rules
contained in this proposal.
To help ensure that TC holders are fully informed of what is
necessary to show compliance with these requirements, as previously
discussed, we are issuing AC 120.XX, and have issued a policy statement
that describes an acceptable means, but not the only means, of
complying with these requirements for developing EWIS ICA and the fuel
tank system ICA required by SFAR 88. AC 120-XX, ``Program to Enhance
Transport Category Airplane
[[Page 58531]]
Electrical Wiring Interconnection System Maintenance,'' provides an
enhanced zonal analysis procedure (EZAP) for completing a review of the
representative airplane covering all areas, including the flight deck
(or cockpit), electrical power center, fuel tank wiring, and
powerfeeder cables. Policy Statement ANM100-2004-10029, ``Process for
Developing Instructions for Maintenance and Inspection of Fuel Tank
Systems Required by SFAR 88,'' provides guidance for identifying ICA,
including any airworthiness limitations, as a result of the fuel tank
system review required by SFAR 88 and compliance with Amendment 102 to
part 25 Appendix H and Sec. 25.981.
Proposed Sec. 25.1805(d) is intended to provide TC holders,
applicants with pending TC-amendment or STC applications, and the FAA
with assurance that they understand what means of compliance are
acceptable and have taken necessary actions, including assigning
sufficient resources, to achieve compliance with this section. This
paragraph is based substantially on ``The FAA and Industry Guide to
Product Certification,'' which describes a process for developing
project-specific certification plans for type certification programs. A
copy of this guide may be found in the docket. This planning
requirement would not apply to future applicants for TC amendments or
STCs because, as described in the guide, this type of planning
routinely occurs at the beginning of the certification process.
The guide recognizes the importance of ongoing communication and
cooperation between applicants and the FAA. Section 25.1805, while
regulatory in nature, is intended to encourage establishment of the
same type of relationship in the process of complying with this
section. In particular, in addition to other necessary information,
paragraph (d)(3) makes it clear that, to the extent that they intend to
use means of compliance different from those already identified as
acceptable by the FAA, it is imperative that they identify those
differences at the earliest possible stage so any compliance issues can
be resolved without risk of unnecessary expenditure of resources or,
ultimately, noncompliance.
Proposed Sec. 25.1805(d) would require TC holders and applicants
to submit to the FAA Oversight Office the following within 90 days
after the effective date of the rule:
A proposed project schedule, identifying all major
milestones, for meeting the compliance dates of this rule.
A proposed means of compliance with this section,
identifying all required deliverables, including all compliance items
and all data to be developed to substantiate compliance. If any
affected person has already initiated compliance, the FAA Oversight
Office will review the results of those efforts to ensure that the
results are acceptable.
A detailed explanation of how the proposed means will be
shown to comply with this section if the affected person proposes a
means of compliance that differs from that described in FAA advisory
material.
A proposal for how the approved ICA will be made available
to affected persons.
It should be noted that this section applies not only to domestic
TC holders and applicants, but also to foreign TC holders and
applicants. In this sense, this section is different from most type
certification programs, where foreign applicants typically work with
their responsible certification authority, and the FAA relies on that
authority's findings of compliance under bilateral airworthiness
agreements. Since this rulemaking is not harmonized in all cases, the
FAA will make all the necessary compliance determinations, and where
appropriate we may accept findings of compliance made by the
appropriate foreign authorities using procedures developed under the
bilateral agreements. The compliance planning provisions of this
section are equally important for domestic and foreign TC holders and
applicants, and we will work with the foreign authorities to ensure
that their TC holders and applicants perform the planning necessary to
comply with the requirements of this section.
One of the items required in the plan is, ``If the proposed means
of compliance differs from that described in FAA advisory material, a
detailed explanation of how the proposed means will comply with this
section.'' FAA advisory material is never mandatory because it
describes one means, but not the only means of compliance. In the area
of type certification, applicants frequently propose acceptable
alternatives to the means described in advisory circulars. But when an
applicant chooses to comply by an alternative means, it is important to
identify this as early as possible in the certification process to
provide an opportunity to resolve any issues that may arise that could
lead to delays in the certification schedule.
The same is true for this requirement. As discussed earlier, TC
holder compliance with this section on time is necessary to enable
operators to comply with the operational requirements of this NPRM.
Therefore, this item in the plan would enable the FAA Oversight Office
to identify and resolve any issues that may arise with the TC holder's
proposal without jeopardizing the TC holder's ability to comply with
this section by the compliance time.
As of the date of this proposal, certain TC holders have
voluntarily started to develop the EWIS EZAP that would be required by
proposed Sec. 25.1805. An EZAP has been completed on certain transport
category airplanes. Although the EZAP used by those TC holders may not
be the version outlined in AC120-XX, it is similar. The FAA would
expect that after issuance of the final rule, these TC holders would
either submit a plan proposing revisions to the EZAP for those model
airplanes to be consistent with the guidance given in AC120-XX, or use
the planning process to show that their EZAP complies with this
section. The FAA Oversight Office will then review the results of those
efforts to ensure that the results are acceptable for compliance with
this section.
Section 25.1805(e) requires that TC holders and applicants correct
a deficient plan, or deficiencies in implementing the plan, in a manner
identified by the FAA Oversight Office. Before the FAA formally
notifies a TC holder or applicant of deficiencies, however, we will
have communicated with them to try to achieve a complete mutual
understanding of the deficiencies and means of correcting them.
Therefore, the notification referred to in this paragraph should
document the agreed corrections.
Because operators' ability to comply with the applicable
operational rules will be dependent on TC holders' and applicants'
compliance with Sec. 25.1805, the FAA will carefully monitor their
compliance and take appropriate action if they fail to achieve
compliance. Failure to comply within the specified time would
constitute a violation of the requirements and may subject the violator
to certificate action to amend, suspend, or revoke the affected
certificate in accordance with 49 U.S.C. Sec. 44709. In accordance
with 49 U.S.C. 46301, it may also subject the violator to a civil
penalty of not more than $25,000 per day per TC until Sec. 25.1805 is
complied with.
C. Other Proposed Changes to Part 25
As explained in the preamble discussion of the proposed subpart H,
some existing rules applying to EWIS would need revision in order to
support the proposed new subpart. Those rules that would be changed by
this proposal are:
25.611
25.855
[[Page 58532]]
25.869
25.1203
25.1301
25.1309
25.1353
25.1357
The changes proposed for them are discussed in the section-by-
section discussion for proposed subpart H. In addition, this NPRM
includes a number of other changes to part 25 requirements for
electrical systems discussed later in the section headed ``Electrical
System Harmonization Rules.'' The remaining changes to part 25 are
discussed below.
Section 25.1357(f) System Power Removal
ATSRAC has proposed adding a requirement that airplane systems
normally requiring power removal have a power switch to accomplish
this, instead of relying on using the circuit breaker. The FAA has
decided that this requirement belongs in Sec. 25.1357.
It is not the intent of the proposal to require that every
electrically powered system in the airplane have a means to remove
power from them other than a circuit breaker. ATSRAC used the phrase
``normally requiring power removal'' to distinguish between airplane
systems normally turned on and off during normal operations, such as
passenger convenience systems, and those systems normally powered at
all times, such as the flightdeck multi-function displays or the flight
management computer. But if, for example, the flight-management
computer did require power cycling regularly, for whatever reason, this
system would then be required to have a means to do this other than
using the circuit breakers.
For systems requiring this power removal design feature, power
should be removed from the system as closely as practical to the source
of power instead of simply deactivating the outputs of the systems
power supplies.
The ability to quickly remove power from an airplane system not
required for the airplane's safe operation is important if an emergency
situation demands isolation of a known or unknown source of fire or
smoke. One of the first things flightcrews are instructed to do when
faced with a fire or smoke emergency is to remove power from the known
source or from all unnecessary systems if the source is unknown. This
is to stop the fire or smoke from spreading. Currently, part 25
regulations do not require systems to have a separate shutoff feature.
But the need for the flightcrew to be able to shut off unnecessary
systems was tragically illustrated during the investigation of the
fatal accident on September 3, 1998, of a Swissair Model MD-11,
discussed earlier in this document.
After that accident, the FAA conducted a special certification
review (SCR) on the IFE system installed on the airplane, and published
its report (``Federal Aviation Administration Special Certification
Review Team Report on: Santa Barbara Aerospace, STC ST00236LA-D,
Swissair Model MD-11 Airplane, In-flight Entertainment System,'' June
9, 2000. A copy of this report is contained in the docket). One of the
team's findings was that the design of the IFE system did not allow the
flightcrew or cabin crew to completely remove electrical power in any
other way than by pulling the system's circuit breakers. The FAA
decided that this was an unsafe condition, and we issued an
airworthiness directive prohibiting operation of MD-11 airplanes with
that particular IFE system installed. The FAA expanded its
investigation and reviewed previously issued STCs that had approved
installation of IFE systems on transport category airplanes. That
investigation identified over 20 STC IFE installations that had the
same design characteristics as the one on the accident MD-11 airplane
(no means to remove power other than by pulling the circuit breaker).
We issued ADs to correct those inadequate IFE system designs. As more
IFE systems with the same design characteristic are identified, ADs
will be issued to correct the identified unsafe condition.
On September 18, 2000, the FAA issued a policy memorandum stating
that a newly certified IFE system should have a way for the flightcrew
or cabin crew to disconnect it from its source of power other than by
using circuit breakers. A copy of this memorandum, titled ``Interim
Policy Guidance for Certification of In-Flight Entertainment Systems on
Title 14 CFR Part 25 Aircraft (Policy Number 00-111-160),'' is in the
docket. Most airplane manufacturers are now equipping IFE systems on
their newly delivered airplanes with a power source disconnection
means. Subsequent policy covering cabin video surveillance systems also
contains the same guidance (Policy Number 01-111-196, ``Interim Summary
of Policy and Advisory Material Available for Use in the Certification
of Cabin Mounted Video Cameras Systems with Flight Deck Displays on
Title 14 CFR Part 25 Aircraft,'' included in the docket). ATSRAC (as
recommended by the ATSRAC Wire Systems Harmonization Working Group and
the ARAC Electrical Systems Harmonization Working Group) believes that
this philosophy should be applied to any airplane system that requires
having its power removed or reset during normal operations. The FAA
agrees with this recommendation.
The proposed Sec. 25.1357(f) would require that airplane systems
needing a capability for having their power removed or reset during
normal operations must be designed so that circuit breakers are not the
primary means to do that. This is a new regulation whose requirements
have not previously existed within part 25 and is a recognition that
any airplane system, including an IFE system, that requires regular
power removal or resetting needs to have a means to do so.
Appendix H to Part 25--Instructions for Continued Airworthiness
As previously noted, improper maintenance, repair, and
modifications often hasten the ``aging'' of EWIS. To properly maintain,
repair, and modify airplane EWIS, certain information must be available
to the designer, modifier, and installer. This information should be
part of the ICA as required by current Sec. 25.1529 and the proposed
Sec. 25.1739.
This proposal would amend Appendix H by adding a new section,
H25.5, to require TC applicants to develop maintenance information for
EWIS as part of the ICA as a requirement for getting a design approval.
The proposed rule would also apply to applicants for design change
approvals (supplemental TCs and amended TCs).
The proposal would require applicants for TCs to prepare ICA for
EWIS that are approved by the FAA Oversight Office, in the form of a
document that is easily recognizable as an EWIS ICA. To prepare these
instructions, they must use an EZAP such as the one described in AC120-
XX, ``Program to Enhance Aircraft Electrical Wiring Interconnection
System Maintenance'' to perform a review of their representative
airplane covering all areas, including the flightdeck (also known as
the cockpit), electrical power center, fuel tank wiring and powerfeeder
cables, as well as the engine. Applicants for design change approvals
would have to perform a similar review for their proposed design
changes.
A zonal analysis procedure is an assessment of the structures and
systems within each physical zone of the airplane. It is used to
develop an inspection program to assess the general condition and
security of attachment of all system components and structures items
contained in the zone, using general visual inspections (GVI). An
enhanced zonal analysis procedure
[[Page 58533]]
(EZAP) is an enhanced version of the zonal analysis procedure. It
focuses on EWIS components. An EZAP-generated inspection program might
call for the use of stand-alone GVI and detailed inspections (DET). A
stand-alone GVI is one that is performed separately from the regularly
scheduled GVI (typically more frequently) and is focused on a
particular area or component. In this case, the focus would be wiring.
So while the zonal analysis procedure would result in a regularly
scheduled GVI for the entire zone, in which each of its systems and
structures are inspected at the same time, the EZAP could result in
additional GVIs or DETs for the EWIS in that zone, which occur more
frequently. These inspection techniques are discussed later in this
section.
An EZAP identifies the physical and environmental conditions
contained in each zone of an airplane, analyzes their effects on
electrical wiring, and assesses the possibilities for smoke and fire.
From such an analysis, maintenance tasks can be developed to prevent
ignition sources and to minimize the possibilities for combustion by
minimizing the accumulation of combustible materials. Such a procedure
would involve dividing the airplane into physical areas, or zones,
including actual physical boundaries such as wing spars, bulkheads, and
cabin floor, and access provisions for the zone, and identifying which
of those zones contain EWIS components. For those zones with EWIS
components, characteristics and components of all systems installed in
the zone would be listed. The EWIS in the zone would be described,
including information on the full range of power levels carried in the
zone. And the presence or possibilities for ignition sources or
accumulation of combustibles would be noted.
Combustibles are any materials that could cause a fire to be
sustained in the event of an ignition source. Examples of combustible
materials would be dust or lint accumulation, contaminated insulation
blankets, and fuel or other combustible liquids or vapors. Wire
contaminants are foreign materials that are likely to cause degradation
of wiring. Wire contaminants can also be combustibles. Some commonly
used airplane liquids, like engine oils, hydraulic fluids, and
corrosion prevention compounds, might be readily combustible, but only
in vapor or mist form. In that case, an assessment must be made of
conditions that could exist within the zone that would convert the
liquid to that form. Combustibles appearing as a result of any single
failure must be considered. An example would be leaks from connection
sites of unshrouded pipes. For the purposes of this new requirement,
the term combustible does not refer to material that will burn when
subjected to a continuous source of heat as occurs when a fire
develops. Combustibles, as used here, will sustain a fire without a
continuous ignition source.
An EZAP must address:
Ventilation conditions in the zone and the density of the
installations that would affect the presence and build-up of
combustibles and the possibilities for combustion. Avionics and
instruments located in the flightdeck and equipment bays, which
generate heat and have relatively tightly packed installations, require
cooling air flow. The air blown into the area for that cooling tends to
deposit dust and lint on the equipment and EWIS components.
Liquid contamination on wiring. Most synthetic oils and
hydraulic fluids, while they might not be combustibles by themselves,
could be an aggravating factor for accumulation of dust or lint. This
accumulation could then present fuel for fire. Moisture on wiring may
increase the probability of arcing from small breaches in the
insulation, which could cause a fire. Moisture on wires that contain
insulation breaches can also lead to ``arc tracking.'' As discussed
previously, arc tracking is a phenomenon in which an electrical arc
forms a conductive carbon path across an insulating surface. The carbon
path then provides a short circuit path through which current can flow.
Short circuit current flow from arc tracking can lead to loss of
multiple airplane systems, structural damage, and fire.
EWIS in close proximity to both primary and back-up
hydraulic, mechanical, or electrical flight controls.
The type of wiring discrepancies that must be addressed if
they are identified by general visual or detailed inspections. A
listing of typical wiring discrepancies that should be detectable
during EZAP-derived EWIS inspections is given in AC120-XXX, Section B
``Guidance for Zonal Inspections.''
Proper cleaning methods for EWIS components.
Once information about such contaminants and combustibles within an
airplane zone is collected, each identified possibility for combustion
would then be addressed to determine whether a specific task could be
performed to reduce that possibility. An example of a specific task to
reduce build-up of combustibles on EWIS components is the use of
temporary protective covers (such as plastic sheeting) over EWIS
components in a zone where corrosion prevention fluids are being used.
This would minimize the amount of fluid contamination of the EWIS
components. Preventing fluid contamination reduces the probability of
other contaminants, like dust and dirt, accumulating on the EWIS
components. If no task can be developed to prevent accumulation of
combustibles in a zone, such as the dust blown through the air by
cooler fans, then tasks must be developed to minimize their buildup,
such as scheduled cleaning.
Developing an ICA to define such tasks would include assessing
whether particular methods of cleaning would actually damage the EWIS
components. Although regular cleaning to prevent potential combustible
build-up would be the most obvious task for an EWIS ICA, other
procedures might also be called for. A detailed inspection of a
hydraulic pipe might be appropriate, for instance, if high-pressure
mist from a pinhole caused by corrosion could accumulate on a wire
bundle in a low ventilation area, creating a possibility for electrical
arcing.
Proximity of EWIS to both primary and back-up hydraulic,
mechanical, or electrical flight controls within a zone would affect
the criticality of inspections needed, their level of detail, and their
frequency. Even in the absence of combustible material, wire arcing
could adversely affect continued safe flight and landing if hydraulic
pipes, mechanical cables, or wiring for fly-by-wire controls are routed
close to other wiring.
The EZAP-generated ICA must be produced in the form of a single
document, easily recognizable as EWIS ICA for that specific airplane
model. The single document is relevant to the maintenance and
inspection aspects of the ICA, and not the standard wiring practices
manual or electrical load analysis, etc.
The ICA must define applicable and effective tasks, and the
intervals for performing them, to:
Minimize accumulation of combustible materials.
Detect wire contaminants.
Detect wiring discrepancies that may not otherwise be
reliably detected by inspections contained in existing maintenance
programs.
As noted earlier, among the types of tasks to be developed from an
EZAP are general visual inspections (GVI) and detailed inspections
(DET). A GVI is defined as a visual examination of an interior or
exterior area, installation, or assembly to detect obvious damage,
failure, or irregularity. This level of inspection is made from within
touching distance of the inspected
[[Page 58534]]
object unless otherwise specified. It is made under normally available
lighting conditions such as daylight, hangar lighting, flashlight, or
droplight and may require removal or opening of access panels or doors.
It may be necessary to use a mirror to improve visual access to all
exposed surfaces in the inspection area. Stands, ladders, or platforms
may be required to gain proximity to the area being checked. It is
expected that the area to be inspected is clean enough to minimize the
possibility that accumulated dirt, grease, or other contaminants might
hide unsatisfactory conditions that would otherwise be obvious. It is
also expected, as an outcome of the EZAP applied to EWIS, that any
cleaning considered necessary would be performed in accordance with
procedures that minimize the possibility of the cleaning process itself
introducing anomalies. The EZAP must identify guidelines to assist
personnel performing a GVI in identifying wiring discrepancies and in
assessing what effect such discrepancies, if found, could have on
adjacent systems, particularly if these include wiring. As discussed
previously, a list of typical wiring discrepancies that should be
addressed is contained in proposed AC120-XX, Section B, ``Guidance for
Zonal Inspections.''
A DET is an intensive examination of a specific item, installation,
or assembly to detect damage, failure, or irregularity. Available
lighting is normally supplemented with a direct source of good lighting
at an intensity considered appropriate. Inspection aids, such as
mirrors, magnifying lenses, or other means, may be necessary. Surface
cleaning and elaborate access procedures may be required. A DET can be
more than just a visual inspection. It may include tactile assessment
to check a component or assembly for tightness and security. Such an
inspection may be needed to ensure the continued integrity of
installations such as bonding jumpers, terminal connectors, etc.
A DET would be required when the developer of the EZAP determines
that a GVI is inadequate to reliably detect anomalies or degradation of
EWIS components. Any detected discrepancies must be corrected according
to the operator's approved maintenance procedures. It is not intended
that the EZAP ICA identify how to correct detected discrepancies.
To prevent improper modification and repair of existing EWIS or the
improper installation of a new EWIS, modification designers and
modification personnel must know the applicable standard wiring
practices, EWIS identification requirements, and electrical load data
for the airplane undergoing modification. The proposed Appendix H 25.5
would also require that the following information be included in ICA
applicable to EWIS:
Standard wiring practices data.
Wire separation design guidelines.
Information to explain the airplane's EWIS identification
method required by the proposed Sec. 25.1711.
Electrical load data and instructions for updating that
data. Such information will help ensure that those modifying,
repairing, or installing new EWIS will not perform any action that will
adversely affect previously certified systems and unintentionally
introduce potential hazards.
Standard wiring practices are defined as standards developed by the
specific airplane manufacturer or industry-wide standards for the
repair and maintenance of EWIS. They include procedures and practices
for the installation, repair, and removal of EWIS components, including
information about wire splices, methods of bundle attachment,
connectors and electrical terminal connections, bonding, and grounding.
Although a standard wiring practices manual is not a design manual, and
those designing a new EWIS modification for a specific model airplane
should not use it as such, it does provide the designer with insight
into the types of EWIS components used by the TC holder and the
procedures recommended by the manufacturer for maintenance or repair
that supports continued airworthiness of the components.
EWIS separation guidelines are important for maintaining the safe
operation of the airplane. Maintenance and repair personnel need to be
aware of the type certificate holders' separation requirements so they
do not compromise separation in previously certified systems. In fuel
tank systems, the separation of certain wires may be critical design
configuration control items and therefore qualify as an airworthiness
limitation. Maintenance personnel need to be aware of these guidelines
and limitations because many times wire bundles must be moved or
removed to perform necessary maintenance. They must be able to readily
identify EWIS associated with systems essential to the safe operation
of the airplane.
Similarly, those who design and install new EWIS need to be aware
of separation requirements so they can use the same methods to develop
the required separation for the EWIS they are adding to the airplane.
This would help to ensure both that newly added EWIS is adequately
separated from other EWIS, airplane system components, and structure so
they do not damage the added EWIS, and that the addition of the new
EWIS does not invalidate separation for previously certified EWIS.
Electrical load data and the instructions for updating that data
are necessary to help ensure that future modifications or additions of
equipment that consume electrical power do not exceed the generating
capacity of the onboard electrical generation and distribution system.
The existing Sec. 25.1351(a)(1) mandates that the required generating
capacity, and the number and kinds of power sources, must be determined
by an electrical load analysis. Typically, after an airplane is
delivered and enters service, it is modified numerous times throughout
its service life. Each addition or deletion of an electrical-power-
consuming system changes the electrical load requirements. The only way
to ensure that the capacity of the overall generating and distribution
system, as well as individual electrical buses, is not exceeded is to
have an up-to-date electrical load analysis. The best way to ensure
that an up-to-date electrical load analysis is maintained is for the
type certificate holder to include such data in the ICA provided with
the airplane when it is first delivered to a customer, along with
recommended practices for keeping it updated as electrical loads are
deleted and added.
D. Part 25 Electrical System Harmonization Rules
At the time the EWIS certification requirements contained in this
proposal were being developed, several existing part 25 certification
requirements were also undergoing revision under a separate joint
harmonization effort with the European JAA. The FAA had tasked ARAC to
develop recommendations for harmonized rules (64 FR 66522). The intent
of that harmonization effort was to develop a common set of standards
between 14 CFR part 25 and JAR-25. As mentioned previously, JAR-25 is
the European counterpart to part 25.
When ATSRAC began developing the EWIS requirements proposed in this
NPRM, the process of developing harmonized proposals was essentially
complete, although NPRMs had not yet been published in the Federal
Register. So ATSRAC worked on the assumption that the harmonized rules
would be in effect by the time this proposal was published, and used
the new proposed harmonized part 25 as the baseline for the proposed
EWIS requirements. This NPRM revises several of the harmonized
[[Page 58535]]
rules to accommodate the proposed new EWIS requirements.
Three of those harmonized part 25 proposals, Sec. 25.869(a), Sec.
25.1353(a), (c)(5), (c)(6), (d), and Sec. 25.1431(d), have already
been adopted as final rules (69 FR 12526). We're revising the new
25.1353(a) in this NPRM. Some of the remaining harmonized rules have
been published as NPRMs. But several others have not. Therefore, to
ensure consistency in the proposed EWIS requirements, those harmonized
requirements on which ATSRAC recommendations are based, and which have
not yet been published as final rules, are included in this NPRM. These
are: Sec. Sec. 25.899, 25.1309, 25.1310, 25.1357, 25.1360, 25.1362,
and 25.1365.
The following discusses the proposed harmonization rules that must
be adopted to support the addition of the proposed part 25 EWIS
certification requirements. We believe the public should be aware of
the background and full reasoning behind each change to these
standards.
Section 25.899 Electrical Bonding and Protection Against Static
Electricity
Proposed Sec. 25.899 would contain requirements for electrical
bonding and protection against static electricity. Current Sec. Sec.
25.581, 25.954, and 25.1316 contain requirements for protecting the
airplane and its systems from the effects of lightning strikes. But the
current requirements do not address the hazards that could occur
because of the accumulation of electrostatic charge. Static electricity
can cause electrical shock hazards to people, ignite fuel vapors, and
cause electromagnetic interference of airplane systems. Proposed Sec.
25.899 would require that electrical bonding and protection against
static electricity be designed to minimize accumulation of
electrostatic charge that could cause human injury from electric shock,
ignition of flammable vapors, or interference with electrical and
electronic equipment. Compliance could be shown by bonding the
components properly to the airframe or by incorporating other
acceptable means to dissipate static charge.
This proposal would adopt a modified version of the current
proposed JAR 25X899. As currently written, the JAR duplicates some of
the lightning protection requirements of JARs 25.581, 25.985, and
25.1316. That proposed JAR 25X899 will be revised as well, and those
duplications removed, for the purposes of this harmonization.
There is currently no Sec. 25.899. This new requirement is
necessary to ensure electrical bonding and static protection is fully
addressed as a design standard. Proposed Sec. 25.899 maintains the
same level of safety as currently exists because it reflects and
codifies current industry practices. The proposed change would affect
airplane manufacturers by requiring compliance with the new sections of
the regulations. However, this would have a minimal effect in practice
because airframe manufacturers must comply with proposed standards when
seeking joint FAA-JAA certification of their products, so there would
be little change required from the standards they have been using to
comply with the existing proposed JAR 25X899.
The FAA has developed advisory material about the requirements for
bonding and static electricity protection in transport category
airplanes. This material is contained in proposed AC 25.899-1.
Section 25.1309 Equipment, Systems, and Installations and Section
25.1310 Power Source Capacity and Distribution.
Proposed new Sec. 25.1310 is composed of material now covered in
Sec. 25.1309(e) and (f). The current standards define an ``essential
load'' on the power supply and the conditions under which those loads
must be supplied. An ``essential load'' is each equipment installation
whose function is required for type certification or by operating rules
and that requires a power supply. These paragraphs require that power
sources must be able to supply those loads under a number of specified
failure conditions. These requirements are not directly related to the
safety and analysis requirements of Sec. 25.1309. For that reason, and
to make them more accessible, we propose to move them to a new section
where they would stand alone. There is no current Sec. 25.1310.
The goal of harmonization was to ``envelope'' to the more stringent
requirements, which in this case are those contained in the current
Sec. 25.1309(e) and (f). The proposal is to adopt as Sec. 25.1310 the
more stringent current Sec. 25.1309(e) and (f). The JAA has agreed to
adopt the same requirements in a new JAR 25.1310 (JAR NPA25df-317).
Current Sec. 25.1309(g) would be redesignated as Sec. 25.1309(e). The
proposed new Sec. 25.1310 and JAR 25.1310 would not be completely
harmonized because JAR 25.1310 contains requirements for maintenance of
airworthiness essential services after failure of any two engines on a
three-engined airplane and makes reference to two JAR Advisory Circular
Joint materials (ACJ). But the proposed standard maintains the same
level of safety as the current regulations. It is in line with current
design practices and will have a minimum effect on the airplane
operators and manufacturers.
There is no current published FAA advisory material for the
proposed rule. ARAC has recommended that the JAR ACJ to 25.1310(a) be
adopted as FAA advisory material because it provides a useful,
acceptable means of compliance. The FAA plans to adopt it.
Section 25.1357 Circuit Protective Devices
Section 25.1357 specifies standards for use, functional
requirements, and installation requirements for electrical circuit
protective devices. These standards protect the airplane's wiring from
electrical faults or malfunctions.
JAR paragraph 25.1357(d) contains a requirement to provide
sufficient spare fuses, formerly located in paragraph (f). The reason
the JAA moved this text from paragraph (f) to (d) was to make it clear
that the spare fuse requirement does not apply to fuses that are
inaccessible in flight. We propose to revise Sec. 25.1357 to move the
spare fuse requirement of paragraph (f) to paragraph (d) to harmonize
with the JAR requirement.
The proposed standard continues to address the underlying safety
issue by providing protection for the airplane's electrical system from
wiring faults or malfunctions, and by ensuring that there is no
confusion about use of spare fuses in flight. It would maintain the
same level of safety relative to the current regulations and is in line
with current industry practice.
Manufacturers and operators of transport category airplanes could
be affected by the proposed change. But since it is in line with
current industry practice and does not result in any practical changes
in requirements or practice, such effects would not be significant.
The JAR paragraph 25.1357(a) references advisory material, ACJ
25.1357(a), which states that the effects of variations in ambient
temperatures on either the protective device or the equipment it
protects must not result in hazards. We intend to revise our current AC
25-1357 to include this ACJ material. The announcement of a new AC on
the effects of temperature variations will be published in the Federal
Register once it is available to the public. Comments on the proposed
AC will be invited in that notice.
Section 25.1360 Precautions Against Injury
Also to harmonize with the standards of JAR, the FAA proposes to
add a new section, Sec. 25.1360, concerning electric
[[Page 58536]]
shock and burn protection. Currently, there is no part 25 requirement
for precautions against injury from electrical shock and burns. Adding
the JAR requirement to part 25 would increase safety. The proposed JAR
25X1360, with its related ACJ material, would require that the
electrical system and equipment must be designed to minimize risk of
electrical shock and burns to the crew, passengers, and maintenance and
servicing personnel during normal operations. The ACJ provides advisory
material for high voltages and high temperatures and a means of
compliance to the requirements.
The proposed action is to harmonize the regulations by the adoption
of JAR 25X1360 and its ACJ material in its entirety. The proposed
standard is more stringent for part 25 because it adds a new
requirement and new advisory material. But it is in line with current
industry practice, and therefore would maintain the level of safety.
The FAA intends to publish advisory material that adopts the
existing JAA advisory material.
Section 25.1362 Electrical Supplies for Emergency Conditions.
The FAA proposes to add a new section, Sec. 25.1362, about
electrical supplies for emergency conditions. There is no part 25
standard addressing electrical supplies for emergency conditions
equivalent to JAR 25.1362. Partial coverage is provided by Sec. Sec.
25.1189, 25.1195, 25.1309, and 25.1585.
The JAR 25.1362 and associated ACJ material were created to ensure
that electrical supplies for emergency functions (such as fuel and
hydraulic shut-off valves) are maintained so they are operable after
the flight crew has switched off the main power sources. This is
necessary so emergency procedures can be performed. Since there is no
equivalent standard to JAR 25.1362 in part 25, but partial coverage is
provided by Sec. Sec. 25.1189, 25.1195, 25.1309, and 25.1585,
application of JAA standards by U.S. manufacturers and aircraft
operators has sometimes resulted in different designs for the powering
of appropriate emergency functions.
The proposed action would adopt a new Sec. 25.1362 harmonized to a
revised JAR 25.1362. The new harmonized standard would provide for a
consistent application of the standards. The ACJ would be revised and
adopted as a new AC by the FAA. This proposed rule and advisory
material would provide flexibility by allowing either an appropriate
airplane flight manual (AFM) procedure or design implementation to
achieve compliance with the standards.
This proposal addresses the underlying safety issue by ensuring
that appropriate electrical power supplies are maintained to emergency
services after the main power sources have been switched off by the
flightcrew. The proposal increases the level of safety by focusing on
appropriate methods to ensure that electrical power is provided for
emergency functions during emergency landing or ditching conditions. It
is in line with current industry practice. Another option considered
was to adopt the existing JAR and ACJ into 14 CFR. But revising the JAR
and the ACJ material and creating a new Sec. 25.1362 and AC 25-1362
results in a harmonized standard that would provide greater flexibility
for compliance.
Since this proposed change is in line with current design
practices, the effect is considered to be minimal for aircraft
operators and manufacturers affected by this change.
There is no FAA advisory material available. This proposal would
create a new AC 25-1362 harmonized with ACJ 25X1362.
Section 25.1365 Electrical Appliances, Motors, and Transformers
The FAA proposes to add a new section, Sec. 25.1365, within the
``Miscellaneous Equipment'' section of subpart F, concerning design and
installation of domestic appliances. The term ``domestic appliance'' is
used to refer to those items placed on the airplane to provide service
amenities to passengers. Examples of domestic appliances are cooktops,
ovens, microwave ovens, coffee makers, water heaters, refrigerators,
and toilet flush systems. In turn, domestic systems are those such as
lavatories or galleys, that may contain one or more domestic
appliances. IFE equipment, however, is not considered equipment that
falls under the definition of a domestic appliance. Proposed Sec.
25.1365 is now covered by Sec. 25.1309(b), which does not specifically
address electrical appliance motors and transformers.
The proposed Sec. 25.1365 would require that domestic appliances
be designed and installed so that in the event of failures, the
requirements of Sec. Sec. 25.1309(b), (c), and (d) would be satisfied.
It would further require that galleys and cooking appliances be such as
to minimize risk of overheating or fire and that they be installed to
prevent damage or contamination of other equipment from fluids or
vapors resulting from spillage during use of the appliances. It would
also require that electric motors and transformers be provided with a
thermal protection device unless it can be shown that the circuit
protective device required by Sec. 25.1357(a) would be sufficient to
show compliance with the requirements of Sec. 25.1309(b).
Adoption of the proposal would address concerns that faulty galley
heating equipment (ovens) often cause smoke or fire in the cabin, and
that circuit protection devices used in motor power supplies for those
appliances have not always provided enough protection against failures.
The proposed standard would be an improvement over current safety
practices because current part 25 does not specifically address
electrical appliance motors and transformers. The FAA considers that a
new Sec. 25.1365 specifically addressing domestic appliances is the
most appropriate way to increase the level of safety. The JAA is
adopting the same requirement as JAR 25.1365.
Aircraft operators and manufacturers, together with suppliers of
galley and electrical equipment, could be affected by this change.
Since newly certificated aircraft may have to be supplied with newly
designed galley equipment, airplane operators may elect to introduce
the same new equipment into their existing fleet to maintain fleet
commonality.
A new AC 25-1365 will be developed and an announcement of its
availability for comment will be published in the Federal Register.
E. Proposed Changes to Part 91, 121, 125, and 129 Operating Rules for
Fuel Tank Systems and EWIS and Other Existing Continued-Airworthiness-
Related Rules
As discussed earlier, the proposed alignment of the ICA
requirements for EWIS and the fuel tank system is a result of an FAA
review and realignment of the Aging Airplane Program. We have
determined that certain compliance dates in the existing rules and
pending proposals could be better aligned. Other changes to the rules
and proposals are necessary to increase the cost-effectiveness of these
rules and proposals. Therefore, we have decided to revise those
requirements and proposals and to align the compliance schedules as
nearly as possible. This effort also includes a proposal to create new
subparts in parts 25 (subpart I, discussed earlier), 91, 121, 125, and
129. These new subparts would contain certain rules in this proposal
and other existing and future rules that pertain to the support of
[[Page 58537]]
continued airworthiness, in particular, rules addressing aging airplane
issues. The FAA believes that inclusion of certain rules under the new
subparts will improve the reader's ability to readily identify rules
pertinent to continued airworthiness.
The table below illustrates what proposed and existing requirements
will be included in these new subparts. Each of these new subparts is
titled ``Continued Airworthiness.'' The proposed new subparts consist
of relocated, revised, and new regulations pertaining to continued
airworthiness of the airplane. Unless we say otherwise, our purpose in
moving requirements to these new subparts is to ensure easy visibility
of those requirements applicable to the continued airworthiness of the
airplane. We do not intend to change their legal effect in any other
way.
New Continued Airworthiness Subparts for Parts 25, 91, 121, 125, and 129
----------------------------------------------------------------------------------------------------------------
Part 91 new/ Part 121 new/ Part 125 new/ Part 129 new/
Part 25 new/relocated rules relocated rules relocated rules relocated rules relocated rules
within proposed Subpart I within proposed within proposed within proposed within proposed
Subpart L Subpart Y Subpart M Subpart B
----------------------------------------------------------------------------------------------------------------
Sec. 25.1801--Purpose and Sec. 91.1501-- Sec. 121.901-- Sec. 125.501-- (Proposed Subpart
definition (new). Purpose and Purpose and Purpose and A would contain a
definition (new). definition (new). definition (new). revised Sec.
129.1 and all of
existing part 129
except Sec. Sec.
129.16, 129.32,
and 129.33).
Sec. 25.1803--Reserved........ Sec. 91.1503-- Sec. 121.903-- Sec. 125.503-- Sec. 129.101--
Reserved. Reserved. Reserved. Purpose and
definition (new).
Sec. 25.1805--Electrical Sec. 91.1505-- Sec. 121.905-- Sec. 125.505-- Sec. 129.103--
wiring interconnection systems Repairs Aging airplane Repairs Reserved.
(EWIS) maintenance program assessment for inspections and assessment for
(new). pressurized records reviews pressurized
fuselages (formerly Sec. fuselages
(formerly Sec. 121.368). (formerly Sec.
91.410(a)). 125.248(a)).
Sec. 91.1507-- Sec. 121.907-- Sec. 125.507-- Sec. 129.105--
Fuel tank system Repairs Fuel tank system Aging airplane
maintenance assessment for inspection inspections and
program (new) pressurized program (new) records reviews
(replaces fuselages (replaces for U.S.-
requirements of (formerly Sec. requirements of registered
Sec. 91.410(b)). 121.370(a)). Sec. multiengine
125.248(b)). aircraft
(formerly Sec.
129.33).
Sec. 121.909-- .................. Sec. 129.107--
Supplemental Repairs
inspections assessment for
(formerly Sec. pressurized
121.370a). fuselages
(formerly Sec.
129.32(a)).
Sec. 121.911-- .................. Sec. 129.109--
Electrical wiring Supplemental
interconnection inspections for
systems (EWIS) U.S.-registered
maintenance aircraft
program (new). (formerly Sec.
129.16).
Sec. 121.913-- .................. Sec. 129.111--
Fuel tank system Electrical wiring
maintenance interconnection
program (new) systems (EWIS)
(replaces maintenance
requirements of program (new).
Sec.
121.370(b)).
Sec. 129.113--
Fuel tank system
maintenance
program (new)
(replaces
requirements of
Sec.
129.32(b)).
----------------------------------------------------------------------------------------------------------------
As previously stated, other future rules pertaining to the support
of continued airworthiness would also be contained in these proposed
new subparts. Several such proposals are currently under development.
But because of uncertainties in the timing of adoption of final rules,
it is not always possible to estimate which of the proposals currently
being developed will reach final rule stage first. In order to ensure
that the proposed new subparts for continued airworthiness have been
established in 14 CFR to contain whichever of several new continuing
airworthiness proposals is adopted, the FAA has decided to use a
``building block'' strategy to establish the new subparts.
Until the new subparts have been established in 14 CFR as part of a
final rule, each of several proposals containing new continued
airworthiness rules will include language needed to set up the proposed
subparts. Once one of those proposals becomes final, and the new
continued airworthiness subparts are thus established, then other
continued-airworthiness-related proposals will delete any language
relating to setting up the new subparts. They will retain only the rule
language pertinent to that specific proposal.
A result of this ``building block'' strategy of proposed rulemaking
is the possibility that two or more NPRMs may appear in the Federal
Register proposing the same new continued airworthiness subparts for 14
CFR at the same time. The language setting up the operational rule
subparts will be the same in each rulemaking. But the language setting
up subpart I of part 25 will vary slightly because of differences in
the applicability of each rule. The proposed applicability in proposed
Sec. Sec. 25.1 and 25.1801 will be correct for each NPRM. Otherwise,
commenters addressing each NPRM might be confused by an inconsistency
between the applicability of the subpart and the applicability of the
individual proposed rule sections. And until final decisions are made
on the content of each later NPRM, it would be inappropriate and
potentially misleading for this NPRM to propose that content.
If this NPRM, which has the narrowest applicability of several
[[Page 58538]]
proposals in development, is adopted first, then as each of the other
final rules is adopted, Sec. Sec. 25.1 and 25.1801 would be amended to
expand the applicability to cover what's added in the new rule. For
instance, one proposal might cover holders of existing supplemental
type certificates (STCs), so Sec. 25.1 and Sec. 25.1801, as adopted
in this NPRM, would be amended to reference those holders. If a
proposal applying to them is adopted first, then when this proposal is
adopted, we can remove the proposed Sec. 25.1 and Sec. 25.1801 from
the final rule, because those provisions would already be included in
the previously adopted rule.
When all the proposals currently under development are issued as
final rules, Sec. 25.1 and Sec. 25.1801 will be as broad as they need
to be to cover all of the rules. If any of those rules currently under
development is not issued, then those sections would be only as broad
as is needed for the rules that are adopted. Because the language in
each NPRM will have been appropriate for that specific NPRM, the public
will have been given adequate notice for all of the provisions in the
final versions of those sections.
Paragraph (a) of the ``Purpose and definition'' sections of part
91, subpart L, part 121, subpart Y, part 125, subpart M, and part 129,
subpart B generally describes the applicability of these subparts and
states that the purpose of the various sections in these subparts is to
prescribe requirements to support continued airworthiness. While most
of the requirements of these subparts would address the need for
improved maintenance, these subparts may also include requirements to
modify airplanes or take other actions that we consider necessary for
continued airworthiness.
Historically, the only means used by the FAA to impose these types
of requirements was the AD process. Under part 39, ADs address unsafe
conditions that we determine are likely to exist or develop on other
products of the same type design. In recent years, the FAA has
identified a number of fleet-wide continued airworthiness issues,
particularly relating to aging airplanes, that are not limited to
particular type designs. Under these circumstances, general rulemaking
may be a more efficient and appropriate way to address these types of
problems than ADs. These new subparts provide locations for these types
of requirements.
Paragraph (b) of these sections provides a definition of the term
``FAA Oversight Office.'' As stated in the discussion of proposed Sec.
25.1801, the FAA Oversight Office is the aircraft certification office
or office of the Transport Airplane Directorate with oversight
responsibility for the relevant type certificate or supplemental type
certificate, as determined by the Administrator. As discussed
previously, the primary means for operators to comply with the
requirements of these subparts would be by implementing programs or
taking other actions developed by the TC and STC holders under proposed
subpart I of part 25. In each case, to ensure compliance with the
relevant subpart I rule, the TC and STC holder deliverables must be
approved by the FAA Oversight Office. Because we expect this will be a
standard approach to compliance with the requirements of these
subparts, we are including this definition in these sections to avoid
having to repeat it in each section within these subparts.
Proposed Changes to Parts 121 (Subpart Y) and 129 (Subpart B)--EWIS
Maintenance Programs
Paragraph (a) states that these sections would apply to transport
category, turbine powered airplanes with a maximum type certificated
passenger capacity of 30 or more, or having a maximum payload capacity
of 7500 pounds or more resulting from the original certification of the
airplane or later increase in capacity. This applicability provision
coincides with that of proposed Sec. 25.1805 and is intended to ensure
that, if a TC or STC holder is required to develop EWIS ICA for an
airplane design, the operator of that airplane is required to implement
them. As discussed previously, certain vintage airplanes would be
excluded from these requirements. This applicability would result in
the coverage of airplanes where the safety benefits and the public
interest are the greatest. This action would affect approximately 7,000
U.S. registered airplanes in parts 121 and 129 operations.
Paragraph (b) of these sections would add requirements for
maintenance programs for EWIS for part 121 certificate holders and part
129 foreign air carriers and foreign operators of U.S. registered
aircraft. Paragraph (c) would require them to develop a maintenance
program for EWIS based on ICA for EWIS prepared by TC or STC holders.
As discussed previously, the changes to part 25 would require both
holders of existing TCs and future applicants for TCs and design
changes to provide affected operators with these ICA.
The compliance date for adopting these maintenance program changes
is December 16, 2008. Assuming this proposal is adopted by mid-2006,
this proposal would give operators 30 months after the effective date
of the final rule to make these changes. Because the proposed
compliance date in Sec. 25.1805 for holders of existing TCs is
December 16, 2007, operators would have one year after that date to
comply with this section.
For pending and future design changes approved after December 16,
2008, operators incorporating such a change would have to revise their
maintenance program to incorporate EWIS ICA before returning the
airplane to service.
Paragraph (d) would require that operators keep their EWIS
maintenance programs current as they modify their airplanes. As
discussed earlier, the proposed changes to part 25 would ensure that,
for modifications affecting EWIS, the applicant for the design approval
will provide necessary revisions to the ICA. This paragraph would
ensure that operators installing those modifications on their airplanes
would revise their maintenance program to incorporate these ICA
revisions.
Paragraph (e) would require that the maintenance program changes
required by these sections be approved by the operator's principal
inspector. We are in the process of developing guidance for principal
inspectors to ensure that their reviews are consistent and focused on
the key implementation issues.
Assuming this proposal is adopted by mid-2006, this proposal would
give the affected air carriers and operators 30 months after the
effective date of the final rule to incorporate those ICA for EWIS into
their manuals. Thereafter, inspections and maintenance of EWIS and fuel
tank systems must be carried out at the intervals specified in the
operator's maintenance program.
Many problems caused by inadequate wire maintenance practices have
been discussed previously in this document. Much effort has been
devoted to identifying the maintenance practices that could either
prevent such incidents and accidents from occurring again or mitigate
their causes. The purpose of this new section is to ensure that
enhanced EWIS and fuel tank system maintenance techniques are put into
practice on a continuing basis in airplane maintenance programs. Proper
use of existing methods, techniques, and practices, combined with
knowledge gained through ATSRAC activities, service history, research,
and analysis, will result in improved wire system safety.
[[Page 58539]]
Proposed Changes to Parts 91 (Subpart L), 121 (Subpart Y), 125 (Subpart
M), and 129 (Subpart B)--Fuel Tank Maintenance Programs
These proposals would require part 91 and part 125 operators, part
121 certificate holders, and part 129 foreign air carriers and foreign
persons operating U.S. registered airplanes to incorporate fuel tank
system ICA into their inspection or maintenance programs. As discussed
earlier, one of the main objectives of this rulemaking is to align the
operational requirements for fuel tank maintenance programs with the
proposed requirements for EWIS maintenance programs. To that end,
except as discussed below, the current fuel tank requirements would be
revised to be parallel with the EWIS operational requirements discussed
earlier. We provide the justification for these parallel provisions in
the earlier discussion of the EWIS proposal, and it is not repeated
here.
Part 91 and part 125 operators are required to have an inspection
program. Part 121 air carriers are required to have an inspection
program and a program covering maintenance, preventive maintenance, and
alterations for their airplanes. As provided by Sec. 43.13(a),
operators may choose to follow the maintenance instructions developed
by the TC holder or they may develop their own maintenance
instructions, as long as they are acceptable to the Administrator. But
they must comply with the airworthiness limitations section of the ICA.
Foreign persons or foreign air carriers operating a U.S. registered
aircraft are required to have a maintenance program approved by the
Administrator.
Because of the Fuel Tank Safety Rule, the above-listed operators
and air carriers must now incorporate instructions for inspection and
maintenance of the fuel tank system into their inspection or
maintenance programs. These instructions must address the actual
configuration of the fuel tank systems and they must be approved by the
FAA aircraft certification office (ACO) having cognizance over the TC
for the affected airplane. The compliance time for incorporation of the
fuel tank system instructions for inspection and maintenance into the
inspection or maintenance programs was changed on July 30, 2004 to
December 16, 2008. The reasons for that change were briefly outlined
earlier in this document in the discussions about rule alignment. This
proposal would change the current requirements for the instructions for
fuel tank inspections and maintenance that must be incorporated into
operators' and air carriers' inspection or maintenance programs in the
following ways:
The FAA Oversight Office must approve ICA for the fuel
tank system, and the operator's principal inspector or Flight Standards
District Office (FSDO) must approve the operator's program changes
incorporating those ICA.
The current rule requires the ACO to approve individual operator
fuel tank maintenance programs. The FAA recognizes that, as long as the
ICA are approved by the ACO, ACO approval of the operators' maintenance
program changes incorporating those ICA imposes unnecessary burdens on
both the operators and the ACOs. With this proposed change, principal
inspectors or the cognizant FSDO would be responsible for reviewing and
approving program changes to address fuel tank safety. But, as stated,
the ICA on which the operator's program is based must be approved by
the FAA Oversight Office.
The instructions for fuel tank maintenance and inspection
developed by the TC holders will be referenced as the ``fuel tank
ICA.'' The previous rule language referred to ``instructions for
maintenance and inspection of the fuel tank system,'' even though it
was widely understood throughout the industry that these instructions
would be contained in the ICA. Because these requirements are now being
aligned with the proposed requirements for EWIS to facilitate operator
compliance, and the EWIS requirements refer to ICA as the place where
EWIS maintenance instructions may be found, the FAA believes that using
a consistent term to refer to the required information in both rules
would clarify the common intent of the requirements and make them
easier for operators to understand.
The fuel tank ICA must address the fuel tank system as
defined by the airplane's TC, any supplemental TCs, and any field
approved incorporated auxiliary fuel tank systems. The current
requirements mandate that the ICA must be developed for the ``actual
configuration of the fuel tank systems of each affected airplane.''
That wording, however, proved to be unclear to many in the industry.
The changed language is proposed to clarify the original intent.
To further clarify what STCs should be included, the FAA has
created a list by airplane model of STCs affected by this proposed
rule. That list has been placed in the docket for this rulemaking and
may also be viewed at http://qps.airweb.faa.gov/QuickPlace/sfar88ops/Main.nsf.
The holders of those STCs, as well as the TC holders for the
affected airplane models, must develop the ICA as required by SFAR 88.
We are also proposing to make it clear that the operator is required to
develop the maintenance instructions for field-approved auxiliary fuel
tanks. Because there is no other design approval holder for these
tanks, there is no other person in a better position to develop these
instructions. As with the original requirements of the Fuel Tank Safety
Rule, we expect that operators who do not have the expertise to develop
these instructions will be able to contract with experts to help them.
The proposed operational rules also make it clear that they apply
to ICA developed under SFAR 88, to ICA developed for new or amended
certificates under Sec. 25.1529 Amendment 102, and to any later
revisions to those ICA. These proposed operational rules would require
that operators revise their maintenance and inspection programs to
incorporate ICA changes associated with alterations affecting the fuel
tank ICA. This is necessary because an alteration may invalidate
existing fuel tank system ICA, and compromise the safety objectives of
the proposed rules.
H. Advisory Circulars
As indicated in the discussion of ATSRAC recommendations that
appeared earlier in this document, the advisory committee has produced
four guidance documents as products of the working group activities
that have contributed to this proposed rule. Those guidance documents
are on maintenance, training, and standard wiring practices manuals, as
well as on the proposed new subpart H. We have used these documents as
the basis for developing the accompanying advisory circulars. Notices
of availability for comment for the training, standard wiring
practices, and subpart H ACs are published elsewhere in the Federal
Register. Notice of availability for the maintenance AC will be
published as soon as possible.
Advisory materials for the design approval holder (DAH)
requirements of subpart I and for the part 25 electrical system
harmonization rules are also made available in notices of availability
for comment published elsewhere in the Federal Register.
In addition, guidance material entitled ``Process for Developing
Instructions for Maintenance and Inspection of Fuel Tank Systems
Required by SFAR 88'' was made available as a policy statement on May
28, 2004 at http://www.airweb.faa.gov/rgl. Comments have been received
and are being reviewed. Advisory Circular 25.981-1B, ``Fuel Tank
Ignition Source
[[Page 58540]]
Prevention Guidelines,'' gives guidance on showing compliance to
certification requirements for prevention of ignition sources within
the fuel tanks of transport category airplanes. It also gives guidance
on developing ICA for fuel tank systems. It can be found in the docket
for this NPRM.
VI. Regulatory Analyses and Notices
Authority for This Rulemaking
The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code. Subtitle I, section 106
describes the authority of the FAA Administrator. Subtitle VII,
Aviation Programs, describes in more detail the scope of the agency's
authority. This rulemaking is promulgated under the authority described
in subtitle VII, part A, subpart III, section 44701, ``General
requirements.'' Under that section, the FAA is charged with promoting
safe flight of civil aircraft in air commerce by prescribing--
Minimum standards required in the interest of safety for
the design and performance of aircraft;
Regulations and minimum standards in the interest of
safety for inspecting, servicing, and overhauling aircraft; and
Regulations for other practices, methods, and procedures
the Administrator finds necessary for safety in air commerce.
This regulation is within the scope of that authority because it
prescribes--
New safety standards for the design of transport category
airplanes, and
New requirements that are necessary for safety for the
design, production, operation, and maintenance of those airplanes, and
for other practices, methods and procedures relating to those
airplanes.
Paperwork Reduction Act
This proposal contains the following new information collection
requirements. As required by the Paperwork Reduction Act of 1995 (44
U.S.C. 3507(d)), the Department of Transportation has submitted the
information requirements associated with this proposal to the Office of
Management and Budget for its review.
Title: Enhanced Airworthiness Program for Airplane Systems/Fuel
Tank Safety (EAPAS/FTS).
Summary: This proposal consists of regulatory changes applying to
wiring systems and fuel tank systems in transport category airplanes.
Some of those changes would require new information collection. The
proposed new information requirements and the persons who would be
required to provide that information are described below.
Required Information, Use, and Respondents
(1) Proposed Sec. 25.1711 would require that electrical wiring
interconnection systems (EWIS) components be labeled to identify the
component, its function, and its design limitations, if any. If the
EWIS is part of a system that requires redundancy, the labeling would
also include component part number, function, and separation
requirements for bundles. This specificity of labeling would be
required to ensure that maintenance can be handled properly and with
the appropriate caution for maintaining the safety features the wiring
system was designed to provide. The information marked on the wires
would be used by maintenance personnel for repair and cautionary tasks,
and by modifiers so that original safety features are retained during
modifications. The future airplane manufacturer and anyone who modifies
the airplane would bear the burden of this labeling requirement.
(2) Proposed Sec. 25.1805 would require that existing TC holders
develop Instructions for Continued Airworthiness (ICA) for EWIS.
Applicants for approval of design changes would be required to develop
revisions to those EWIS ICA for any modifications to the airplane that
might affect them. Proposed Sec. 25.1739 and Appendix H would apply
the requirement for EWIS ICA to future applicants for TCs. EWIS ICA
would be used by operators to prepare their maintenance programs. This
requirement would be necessary to ensure that wiring is properly
maintained and inspected to avoid problems that could affect safety.
(3) Proposed subpart I would also require that TC holders submit to
the FAA a plan detailing how they intend to comply with its
requirements. This information would be used by the FAA to assist the
TC holder in complying with requirements. The compliance plan would be
necessary to ensure that TC holders fully understand the requirements,
correct any deficiencies in planning in a timely manner, and are able
to provide the information needed by the operators for the operators'
timely compliance with the rule.
(4) Anyone operating an airplane under part 121 would be required
to revise their existing maintenance program to incorporate the
maintenance and inspection tasks for EWIS contained in the EWIS ICA
required by subpart I. The information incorporated into the
maintenance program would be used by maintenance personnel to maintain
the integrity of airplane wiring systems. This requirement would be
necessary to ensure that wiring is properly maintained and inspected to
avoid problems that could affect safety.
(5) As a result of the revised maintenance programs that would be
required for airplanes operating under part 121, maintenance personnel
will be performing inspections and maintenance procedures to address
safety issues specific to wiring systems. Although this NPRM does not
specifically require new training, existing Sec. 121.375 requires that
certificate holders or persons performing maintenance have a training
program to ensure that persons determining the adequacy of such work
(including inspectors) are fully informed about the procedures and
techniques involved and are competent to perform them. To comply with
this requirement in relation to proposals for revised maintenance
programs for EWIS included in this NPRM, certificate holders would be
required to develop any additional training program needed to ensure
that the appropriate personnel are adequately prepared to carry out the
revised maintenance programs.
(6) The proposed revision to part 25 Appendix H would require that
future manufacturers include acceptable EWIS practices in their ICA,
presented in a standard format. This information would be used by
maintenance personnel for wiring maintenance and repairs. The
requirement is necessary because information about cautionary tasks
during maintenance that can prevent situations that could compromise
safety need to be available to maintenance personnel. Standard wiring
practices manuals, in which this information is presented, often differ
from manufacturer to manufacturer and so are difficult for maintenance
personnel to find specific information in. The requirement for a
standard format is meant to correct this. Because of this proposal,
manufacturers would change their Standard Wiring Practices Manuals
(SWPM).
Annual Burden Estimate
To provide estimates for the burden associated with this NPRM, the
FAA developed categories corresponding to information collection
impacts of requirements contained in the proposal. The summary table
below contains the impacted entities, average annual hours and hardware
costs, and the corresponding average annual cost. Details of the
estimates are in the paragraphs below.
[[Page 58541]]
----------------------------------------------------------------------------------------------------------------
Proposed Average Average
Entities impacted requirement Hardware cost annual hours annual cost
----------------------------------------------------------------------------------------------------------------
Airplane Manufacturers......... Wire ............................ 12,046 $430,524
identification
(30 seconds per
label).
Airplane Manufacturers......... Label............ 5 cents per label........... .............. 72,275
Airplane Modifiers............. Wire ............................ 18,417 658,224
identification
(30 seconds per
label).
Airplane Modifiers............. Label............ 5 cents per label........... .............. 110,500
Existing TC Holders............ Develop ICA...... ............................ 15,743 868,699
Future TC Applicants........... Develop ICA...... ............................ 3,578 197,434
Future STC Applicants.......... Develop ICA...... ............................ 57,828 3,190,949
Airplane Manufacturers......... Revise SWPM...... ............................ 1,035 57,111
Airplane Manufacturers......... Develop ............................ 132 7,284
Compliance Plan.
Airplane Operators............. Revise ............................ 2,744 151,414
Maintenance
Program.
Airplane Operators............. Develop Training ............................ 2,376 131,108
Program.
-----------------
Total...................... ................. ............................ 113,899 5,875,522
----------------------------------------------------------------------------------------------------------------
Proposed Sec. 25.1711 would affect airplane manufacturers by
requiring additional labeling. Over the 25-year period of analysis,
manufacturers would label on average 413 airplanes yearly. The FAA
estimates that an additional 3,500 labels might be added to wires in
each part 25 airplane, for 1,445,500 labels annually. The additional
identification requirement would take roughly 30 seconds, requiring
approximately 12,046 annual hours. Using the fully burdened hourly cost
of a mechanic ($35.74), the average annual hourly burden for the wire
identification requirement on manufacturers is $430,524.
The estimated cost resulting from information collection from TC
holders also considers the additional cost of labels. The additional
manufacturer identification requirements would require roughly
1,445,500 labels annually. Industry representatives provided the FAA
with cost estimates for each label of approximately 5 cents. The
estimated annual corresponding cost is $72,275.
Section 25.1711 would also affect airplane modifiers when
electrical wiring supplemental type certificates (STC) are installed on
airplanes. The FAA estimates there would be an additional 200 labels
added each time an affected STC is installed on an airplane. Using 170
as the average annual affected number of STCs, and 65 as the number of
installations per STC, the corresponding total annual number of labels
for STCs is 2,210,000. The identification requirement would take about
30 seconds for each additional label, requiring an annual burden of
roughly 18,417 hours. Using the fully burdened hourly cost of a
mechanic ($35.74), the annual burden on airplane modifiers for the wire
identification requirement is $658,224.
Estimated costs resulting from information collection from STC
applicants consider the additional cost of labels. The additional STC
identification requirements would require roughly 2,210,000 labels
annually. With the cost of each label approximately 5 cents, the
estimated average annual corresponding cost is $110,500.
The proposal would require that existing TC holders develop ICA for
EWIS. Over the period of analysis, the FAA estimates the proposal would
require 15,743 average annual engineering hours, resulting in an
average annual cost of $868,699 (using the fully burdened hourly rate
of $55.18 for an engineer).
Proposed Sec. 25.1805 would also require future TC applicants to
develop ICA for EWIS. The FAA estimates roughly .5 part 25 TCs yearly,
with average annual estimated labor hours to perform the analysis of
3,578. This would result in average annual costs of $197,434.
The proposal would require future applicants for STCs to develop
ICA for EWIS as well. Over the period of analysis, the FAA estimates it
would take 948 annual STC applicants 61 hours to perform the analysis.
With engineering costs of $55.18 per hour, the average annual burden
would be $3,190,949.
Because of this proposal, manufacturers would change their Standard
Wiring Practices Manual (SWPM). The FAA calculates 1,035 as the average
annual hours required to update manuals, resulting in an average annual
burden of roughly $57,111.
Manufacturers would present a plan for approval describing how they
intend to comply with the requirements. The FAA believes the data
contained in this plan would be submitted electronically with no cost
to submit the plan. We estimate 60 labor hours (per airplane model) to
develop a plan and submit data to the FAA. We estimate 3,300 hours for
roughly 55 models. The average annual hours are 132, with corresponding
average annual costs of $7,284 (using the fully burdened hourly cost of
$55.18).
Operators would be required to revise their existing maintenance
program to incorporate the maintenance and inspection tasks for EWIS
contained in the EWIS ICA. Over the period of analysis, the FAA
estimates 68,607 total hours, or 2,744 average annual hours required to
revise existing maintenance programs. Using the fully burdened labor
cost for an engineer, the average annual planning cost would be
$151,414.
The estimated cost to develop training considers the industry's
standard training factor of 200 hours per one hour of prepared training
material. 600 hours is the estimated training development time for the
3-hour training course for each operator. When combined with 99
operators, the total hours would be 59,400 or 2,376 annually. Combined
with the burdened hourly cost of $55.18, the average annual cost for
training development would be $131,108.
The agency is soliciting comments to (1) evaluate whether the
proposed collection of information is necessary for the proper
performance of the functions of the agency, including whether the
information will have practical utility; (2) evaluate the accuracy of
the agency's estimate of the burden; (3) enhance the quality, utility,
and clarity of the information to be collected; and (4) minimize the
burden of the collection of information on those who are to respond,
including through the use of appropriate automated, electronic,
mechanical, or other technological collection techniques or other forms
of information technology (for example, permitting electronic
submission of responses).
Individuals and organizations may submit comments on the
information collection requirement by December 5, 2005, and should
direct them to the address listed in the ADDRESSES section of this
document.
According to the regulations implementing the Paperwork Reduction
[[Page 58542]]
Act of 1995, (5 CFR Part 1320.8(b)(2)(vi)), an agency may not conduct
or sponsor, and a person is not required to respond to, a collection of
information unless it displays a currently valid OMB control number.
The OMB control number for this information collection will be
published in the Federal Register after it is approved by the Office of
Management and Budget.
International Compatibility
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to comply with
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that correspond to these proposed regulations.
Regulatory Evaluation Summary
This portion of the preamble summarizes the FAA's analysis of the
economic impacts of this NPRM. It also includes summaries of the
initial regulatory flexibility determination. We suggest readers
seeking greater detail read the full regulatory evaluation, a copy of
which we have placed in the docket for this rulemaking.
Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 directs that each Federal agency
shall propose or adopt a regulation only upon a reasoned determination
that the benefits of the intended regulation justify its costs. Second,
the Regulatory Flexibility Act of 1980 requires agencies to analyze the
economic impact of regulatory changes on small entities. Third, the
Trade Agreements Act (19 U.S.C. 2531-2533) prohibits agencies from
setting standards that create unnecessary obstacles to the foreign
commerce of the United States. In developing U.S. standards, this Trade
Act requires agencies to consider international standards and, where
appropriate, to be the basis of U.S. standards. Fourth, the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4) requires agencies to
prepare a written assessment of the costs, benefits, and other effects
of proposed or final rules that include a Federal mandate likely to
result in the expenditure by State, local, or tribal governments, in
the aggregate, or by the private sector, of $100 million or more
annually (adjusted for inflation).
In conducting these analyses, FAA has determined this proposal: Has
benefits that justify its costs, is not an economically ``significant
regulatory action'' as defined in section 3(f) of Executive Order
12866, and is ``significant'' as defined in DOT's Regulatory Policies
and Procedures; would not have a significant economic impact on a
substantial number of small entities; would not have an effect on
international trade; and would not impose an unfunded mandate on state,
local, or tribal governments, or on the private sector. These analyses,
available in the docket, are summarized below.
Total Costs and Benefits of This Rulemaking
The estimated cost of this NPRM is $474.4 million ($209.2 million
present value) over 25 years. The total estimated benefits are $755.3
million ($340.7 million present value) over 25 years.
Who Is Potentially Affected by This Rulemaking?
Manufacturers of part 25 airplanes.
Operators of large transport category airplanes operating
under FAR Parts 121 & 129.
Applicants for amended type certificates and supplemental
type certificates.
Cost Assumptions and Sources of Information
Discount rate--7%
Period of analysis--25 Years, 2005 through 2029
Burdened labor rate (as shown in key assumptions & labor rates in
regulatory evaluation)--
Aerospace engineers--$55.18/hour
Maintenance personnel--$35.74/hour
Value of fatality avoided--$3.0 million (Source: ``Revised Departmental
Guidance, Treatment of Value of Life and Injuries in Preparing Economic
Evaluations,'' Office of the Secretary of Transportation Memorandum'',
January 29, 2002)
Fleet--FAA Flight Standards (SPAS Database)
Fleet Growth (3.82% per year) & Passenger Occupancy Rates (75%)--
FAA Aerospace Forecasts Years 2003-2014
Failures, Incidents and Accidents--The National Aviation Safety
Data Analysis Center
Aircraft Value--Economic Values for Evaluation of Federal Aviation
Administration Investment and Regulatory Programs 1998
Articles Referenced
Wright, T.P. ``American Methods of Aircraft Production,'' 1939.
Wojcik, Leonard A., ``Models To Understand Airline and Air Traffic
Management Authority Decision-Making Interactions in Schedule
Disruptions: From Simple Games to Agent-Based Models,'' Handbook of
Airline Strategy, 1992.
Irrgang, M.E., ``Airline Irregular Operations,'' Handbook of Airline
Economics, 1995.
Alternatives We Considered
Alternative 1--Require operators to clean & inspect each airplane
every C-check or every three years, causing an additional $192.5
million ($79.9 million present value) in cleaning and inspection costs,
and an additional $104.0 million ($38.6 million present value) in
downtime.
This option would result in additional costs of $296.5 million
($118.5 million present value) with no commensurate increase in
benefits.
Alternative 2--Require EWIS training for four groups of people in
addition to maintenance workers. The groups and additional costs are:
Electrical/avionic engineers--$4.0 million ($2.4 million
present value).
Individuals involved in engineering or planning work--$0.4
million ($0.4 million present value).
Flight deck crew--$260.0 million ($126.1 million present
value).
Cabin crew-$91.5 million ($44.4 million present value).
To train these individuals, operators would develop additional
courses. The FAA estimates an additional $25.2 million ($24.1 million
present value) to develop the necessary training material.
The total estimated additional cost of this alternative is
approximately $381.1 million ($197.4 million present value) with no
commensurate increase in benefits.
Benefits of This Rulemaking
The FAA estimates $755.3 million ($340.7 million present value) as
the total benefits of this proposal.
In the table below, categories of benefits are shown. The middle
column gives the nominal values of quantified benefits, while the
right-hand column gives the total incremental present value benefits
broken down by category type.
[[Page 58543]]
------------------------------------------------------------------------
Nominal
Benefits values Present value
(millions) (millions)
------------------------------------------------------------------------
Non Fatal & Fatal Accidents:
Non Fatal events.................... $56.0 $26.1
Fatal events........................ 507.0 236.3
-----------------
Total........................... 563.0 262.4
=================
EWIS Operational Improvements:
Averted delays...................... 21.2 8.3
Averted unscheduled landings........ 152.4 62.4
Averted IFE failures................ 18.7 7.6
-----------------
Total........................... 192.3 78.3
=================
Total--All Benefits......... 755.3 340.7
------------------------------------------------------------------------
Costs of This Rulemaking
The FAA estimates $474.3 million ($209.2 million present value) as
the total cost of this proposal.
In the table below, the left-hand column specifies the cost
component by 14 CFR part, the middle column gives the nominal cost, and
the right-hand column gives the total incremental present value costs
by 14 CFR part.
------------------------------------------------------------------------
Nominal
Cost component values Present value
(millions) (millions)
------------------------------------------------------------------------
Part 25 Harmonization................... 0 0
Part 25 Subpart H....................... $131.9 $53.8
Part 25 Subpart I....................... 23.3 20.3
Part 121 ICA............................ 319.1 135.1
Parts 91/121/125--Fuel Tank............. (*)
-----------------
Total................................. 474.3 209.2
------------------------------------------------------------------------
* De minimus.
Initial Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a
principle of regulatory issuance that agencies shall endeavor,
consistent with the objective of the rule and of applicable statutes,
to fit regulatory and informational requirements to the scale of the
business, organizations, and governmental jurisdictions subject to
regulation.'' To achieve that principle, the RFA requires agencies to
solicit and consider flexible regulatory proposals and to explain the
rationale for their actions. The RFA covers a wide-range of small
entities, including small businesses, not-for-profit organizations, and
small governmental jurisdictions.
Agencies must perform a review to determine whether a proposed or
final rule will have a significant economic impact on a substantial
number of small entities. If the agency determines that it will, the
agency must prepare a regulatory flexibility analysis as described in
the Act.
However, if an agency determines that a proposed or final rule is
not expected to have a significant economic impact on a substantial
number of small entities, section 605(b) of the 1980 RFA provides that
the head of the agency may so certify and a regulatory flexibility
analysis is not required. The certification must include a statement
providing the factual basis for this determination, and the reasoning
should be clear.
This proposed rule would not have a significant economic impact on
a substantial number of small entities for the following reasons.
Entities potentially affected by this proposal include part 25
manufacturers, applicants for future amended and supplemental type
certificates, and part 121 operators of large transport category
airplanes.
The FAA uses the size standards from the Small Business
Administration for Air Transportation and Aircraft Manufacturing, which
specify companies having less than 1,500 employees as small entities.
The current United States part 25 airplane manufacturers include:
Boeing, Cessna Aircraft, Gulfstream Aerospace, Learjet (owned by
Bombardier), Lockheed Martin, McDonnell Douglas (a wholly-owned
subsidiary of The Boeing Company), Raytheon Aircraft, and Sabreliner
Corporation. These manufacturers would incur type certificate (TC) and
amended TC costs. Because all U.S. transport-aircraft category
manufacturers have more than 1,500 employees, none are considered small
entities.
Future supplemental type certificate (STC) applicants would incur
additional compliance costs. These STC applicants would incur the cost
only if the expected revenue from the STC would exceed the expected
cost. While future STC costs would be passed on to airplane operators,
it is not possible to determine when and which operator would purchase
and install such a future STC. Because a future STC applicant would
incur the additional compliance cost only if the STC would generate
profits, the FAA believes there would not be a significant impact on a
substantial number of STC applicants.
The FAA calculated the economic impact on small-business part 121
operators by dividing the annual compliance cost by the firm's annual
revenue. The annual estimated average annual cost of the proposal would
approach \1/2\ of 1 percent for only two small entities. For the
others, the cost impact would be a few hundredths of 1 percent of
revenue.
[[Page 58544]]
The FAA has determined that: No part 25 manufacturers are small
entities, there would not be a significant impact on a substantial
number of amended TC or STC applicants, the estimated operator
compliance cost as a percent of annual revenue would not be
significant.
Accordingly, pursuant to the Regulatory Flexibility Act, 5 U.S.C.
605(b), the Federal Aviation Administration certifies that this
proposed rule would not have a significant impact on a substantial
number of small entities.
Initial International Trade Impact Assessment
The Trade Agreement Act of 1979 prohibits Federal agencies from
establishing any standards or engaging in related activities that
create unnecessary obstacles to the foreign commerce of the United
States. Legitimate domestic objectives, such as safety, are not
considered unnecessary obstacles. The statute also requires
consideration of international standards and, where appropriate, that
they be the basis for U.S. standards. The FAA has assessed the
potential effect of this proposed rule and determined that it would
impose the same costs on domestic and international entities and, thus,
would have a neutral trade impact.
Initial Unfunded Mandates Assessment
The Unfunded Mandates Reform Act of 1995 (the Act) is intended,
among other things, to curb the practice of imposing unfunded Federal
mandates on State, local, and tribal governments. Title II of the Act
requires each Federal agency to prepare a written statement assessing
the effects of any Federal mandate in a proposed or final agency rule
that may result in an expenditure of $100 million or more (adjusted
annually for inflation) in any one year by State, local, and tribal
governments, in the aggregate, or by the private sector; such a mandate
is deemed to be a ``significant regulatory action.'' The FAA currently
uses an inflation-adjusted value of $120.7 million in lieu of $100
million. This proposed rule does not contain such a mandate. Therefore,
the requirements of Title II of the Unfunded Mandates Reform Act of
1995 do not apply.
Executive Order 13132, Federalism
The FAA has analyzed this proposed rule under the principles and
criteria of Executive Order 13132, Federalism. We determined that this
action would not have a substantial direct effect on the States, on the
relationship between the national Government and the States, or on the
distribution of power and responsibilities among the various levels of
government, and therefore would not have federalism implications.
Plain English
Executive Order 12866 (58 FR 51735, Oct. 4, 1993) requires each
agency to write regulations that are simple and easy to understand. We
invite your comments on how to make these proposed regulations easier
to understand, including answers to questions such as the following:
Are the requirements in the proposed regulations clearly
stated?
Do the proposed regulations contain unnecessary technical
language or jargon that interferes with their clarity?
Would the regulations be easier to understand if they were
divided into more (but shorter) sections?
Is the description in the preamble helpful in
understanding the proposed regulations?
Please send your comments to the address specified in the ADDRESSES
section.
Environmental Analysis
FAA Order 1050.1E identifies FAA actions that are categorically
excluded from preparation of an environmental assessment or
environmental impact statement under the National Environmental Policy
Act in the absence of extraordinary circumstances. The FAA has
determined this proposed rulemaking action qualifies for the
categorical exclusion identified in paragraph 312f and involves no
extraordinary circumstances.
Regulations That Significantly Affect Energy Supply, Distribution, or
Use
The FAA has analyzed this NPRM under Executive Order 13211, Actions
Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). We have determined that it is not
a ``significant energy action'' under the executive order because it is
not a ``significant regulatory action'' under Executive Order 12866,
and it is not likely to have a significant adverse effect on the
supply, distribution, or use of energy.
The following Appendices will not appear in the Code of Federal
Regulations.
Appendix A
List of Acronyms
AC--Advisory Circular
ACJ--Advisory Circular Joint
ACO--Aircraft certification office
AD--Airworthiness directive
AFM--Airplane flight manual
ARAC--Aviation Rulemaking Advisory Committee
ASTF--Aging Systems Task Force
ATA--Air Transport Association
ATSRAC--Aging Transport Systems Rulemaking Advisory Committee
CFR--Code of Federal Regulations
CS--Certification Specifications
CWT--Center wing fuel tank
DET--detailed inspection
EAPAS--Enhanced Airworthiness Program for Airplane Systems
EASA--European Aviation Safety Agency
EUROCAE--European Organization for Civil Aviation Equipment
EWIS--Electrical wiring interconnection systems
EZAP--Enhanced zonal analysis procedure
FAA--Federal Aviation Administration
FQIS--Fuel quantity indicating system
FSDO--Flight Standards District Office
GVI--General visual inspection
ICA--Instructions for Continued Airworthiness
ICAO--International Civil Aviation Organization
IFE--In-flight entertainment
IIWG--Intrusive Inspection Working Group
JAA--Joint Aviation Authority
JAR--Joint Aviation Requirements
MS--Military specification
NPRM--notice of proposed rulemaking
NTSB--National Transportation Safety Board
OMB--Office of Management and Budget
RTCA--Radio Technical Commission for Aeronautics
SAE--Society of Automotive Engineers
SCR--Special certification review
SFAR--Special federal aviation regulation
SFAR 88--Special Federal Aviation Regulation 88--Fuel Tank System
Fault Tolerance Evaluation Requirements--TC- and STC-holder
requirements included in the FTSR
STC--Supplemental type certificate
SWAMP--Severe wind and moisture problem
SWPM--Standard wiring practices manual
TC--Type certificate
TSB--Transportation Safety Board of Canada
WHCSS--White House Commission on Aviation Safety and Security
Appendix B
Correlation Between Proposed New Part 25 Regulations and Existing Regulations
----------------------------------------------------------------------------------------------------------------
Proposed new regulation and title Section Based on existing requirements in
----------------------------------------------------------------------------------------------------------------
Sec. 25.1701 Definition............. (a)................................ none
[[Page 58545]]
(b)................................ none
(c)................................ none
(d)................................ none
Sec. 25.1703 Function and (a)(1)............................. Sec. 25.1301(a)
installation: EWIS.
(a)(2)............................. Sec. 25.1301(c)
(a)(3)............................. Sec. 25.1301(d)
(a)(4)............................. none
(b)................................ none
(c)................................ Sec. 25.869(a)(3)
(d)................................ none
Sec. 25.1705 System safety: EWIS.... (a)(1)............................. Sec. 25.1309(b)(1)
(a)(2)............................. Sec. 25.1309(b)(1)
(b)................................ Sec. 25.1309(b)(2)
Sec. 25.1709 System separation: EWIS (a)................................ Sec. 25.1353(a)
(b)(1)............................. Sec. 25.1353(a)
(b)(2)............................. none
(c)................................ Sec. 25.1353(b)
(d)(1)............................. Sec. 25.1351(b)(1)
(d)(2)............................. Sec. 25.1351(b)(2)
(e)(1)............................. Sec. 25.869(a)(3)(i)
(e)(2)............................. Sec. 25.869(a)(3)(ii)
Sec. 25.1353(d)(3)
(f)(1)............................. Sec. 25.869(a)(3)(i)
(f)(2)............................. Sec. 25.869(a)(3)(ii)
Sec. 25.1353(d)(3)
(g)................................ Sec. 25.1353(d)(3)
(h)(1)............................. Sec. 25.1353(d)(3)
(h)(2).............................
(i)(1)............................. Sec. 25.1353(d)(3)
(i)(2).............................
(i)(3).............................
(j)(1)............................. Sec. 25.1353(d)(3)
(j)(2).............................
(k)................................ none
(l)................................ Sec. 25.1353(d)(3)
Sec. 25.1711 Component
identification: EWIS.
(a)................................ Sec. 25.1301(b)
(b)(1)............................. none
(b)(2)............................. none
(c)................................ Sec. 25.1353(d)(2)
(d)................................ none
(e)................................ none
Sec. 25.1713 Fire protection: EWIS.. (a)................................ Sec. 25.869(a)(1)
(b)................................ Sec. 25.869(a)(2)
(c)................................ Sec. 25.869(a)(4)
Sec. 25.1717 Electrical bonding and (a)................................ Sec. 25.899
protection against static
electricity: EWIS.
(b)................................ none
Sec. 25.1719 Systems and functions: (a)................................ none
EWIS.
(b)(1)............................. Sec. 25.773(b)(2)
(b)(2)............................. Sec. 25.981
(b)(3)............................. Sec. 25.1165
(b)(4)............................. Sec. 25.1310
(b)(5)............................. Sec. 25.1316
(b)(6)............................. Sec. 25.1351
(b)(7)............................. Sec. 25.1355
(b)(8)............................. Sec. 25.1360
(b)(9)............................. Sec. 25.1362
(b)(10)............................ Sec. 25.1365
(b)(11)............................ Sec. 25.1431(c)
Sec. 25.1431(d)
Sec. 25.1721 Circuit protection ................................... Sec. 25.1353(d)(1)
devices: EWIS.
Sec. 25.1723 Instruments using a ................................... Sec. 25.1331(a)(2)
power supply: EWIS. Sec. 25.1303(b)
Sec. 25.1725 Accessibility ................................... Sec. 25.611
provisions: EWIS.
Sec. 25.1727 Protection of EWIS..... (a)(1)............................. Sec. 25.855(e)(1)
(a)(2)............................. Sec. 25.855(e)(2)
(b)................................ none
(c)................................ none
Sec. 25.1729 Flammable fluid fire ................................... Sec. 25.863(b)(3)
protection: EWIS.
Sec. 25.1731 Powerplants: EWIS...... (a)................................ Sec. 25.903(b)
(b)................................ Sec. 25.903(d)(1)
[[Page 58546]]
Sec. 25.1733 Flammable fluid shutoff ................................... Sec. 25.1189(d)
means: EWIS.
Sec. 25.1735 Fire detector systems, ................................... none
general: EWIS.
Sec. 25.1737 Powerplant and APU fire (a)................................ Sec. 25.1203(e)
detector system: EWIS.
(b)(1)............................. Sec. 25.1203(f)(1)
(b)(2)............................. Sec. 25.1203(f)(2)
Sec. 25.1739 Instructions for ................................... Sec. 25.1529
Continued Airworthiness: EWIS.
----------------------------------------------------------------------------------------------------------------
The term ``none'' in the above table indicates that the section in the proposed regulation is a new rule.
Appendix C
Correlation Between Existing Part 25 Regulations and Proposed New Regulations
----------------------------------------------------------------------------------------------------------------
Existing regulation and title Section Proposed new regulation
----------------------------------------------------------------------------------------------------------------
Sec. 25.611 Accessibility provisions ................................... Sec. 25.1725
Sec. 25.773 Pilot compartment view.. (b)(2)............................. Sec. 25.1719(b)(1)
Sec. 25.855 Cargo or baggage (e)(1)............................. Sec. 25.1727(a)(1)
compartments.
(e)(2)............................. Sec. 25.1727(a)(2)
Sec. 25.863 Flammable fluid fire (b)(3)............................. Sec. 25.1729
protection.
Sec. 25.869 Fire protection: systems (a)(1)............................. Sec. 25.1713(a)
(a)(2)............................. Sec. 25.1713(b)
(a)(4)............................. Sec. 25.1713(c)
(a)(3)(i).......................... Sec. 25.1709(e)(1)
(a)(3)(ii)......................... Sec. 25.1709(e)(2)
Sec. 25.1709(f)(1)
Sec. 25.1709(f)(2)
(a)(4)............................. Sec. 25.1713(c)
Sec. 25.899 Electrical bonding and ................................... Sec. 25.1717(a)
protection against static electricity.
Sec. 25.903 Engines................. (b)................................ Sec. 25.1731(a)
(d)(1)............................. Sec. 25.1731(b)
Sec. 25.1165 Engine ignition systems ................................... Sec. 25.1719(b)(3)
Sec. 25.1189 Shutoff means.......... (d)................................ Sec. 25.1733
Sec. 25.1203 Fire detector system... (e)................................ Sec. 25.1737(a)
(f)(1)............................. Sec. 25.1737(b)(1)
(f)(2)............................. Sec. 25.1737(b)(2)
Sec. 25.1301 Function and (a)................................ Sec. 25.1703(a)(1)
installation.
(c)................................ Sec. 25.1703(a)(2)
(b)................................ Sec. 25.1711(a)
(d)................................ Sec. 25.1703(a)(3)
Sec. 25.1303 Flight and navigation (b)................................ Sec. 25.1723
instruments.
Sec. 25.1309 Equipment, systems, and (b)(1)............................. Sec. 25.1705(a)(1)
installations. Sec. 25.1705(a)(2)
(b)(2)............................. Sec. 25.1705(b)
(e)................................ Sec. 25.1707
(f)................................ Sec. 25.1707
Sec. 25.1316 System lightning ................................... Sec. 25.1719(b)(5)
protection.
Sec. 25.1331 Instruments using a (a)(2)............................. Sec. 25.1723
power supply.
Sec. 25.1351 General................ (b)(1)............................. Sec. 25.1709(d)(1)
(b)(2)............................. Sec. 25.1709(d)(2)
Sec. 25.1353 Electrical equipment (a)................................ Sec. 25.1709(b)(1)
and installations.
(a)................................ Sec. 25.1709(a)
(b)................................ Sec. 25.1709(c)
(d)(1)............................. Sec. 25.1721
(d)(2)............................. Sec. 25.1711(c)
(d)(3)............................. Sec. 25.1709(e)(1)
Sec. 25.1709(e)(2)
(d)(3)............................. Sec. 25.1709(f)(1)
Sec. 25.1709(f)(2)
(d)(3)............................. Sec. 25.1709(g)
(d)(3)............................. Sec. 25.1709(h)(1)
Sec. 25.1709(h)(2)
(d)(3)............................. Sec. 25.1709(i)(1)
Sec. 25.1709(i)(2)
Sec. 25.1709(i)(3)
(d)(3)............................. Sec. 25.1709(j)(1)
Sec. 25.1709(j)(2)
(d)(3)............................. Sec. 25.1709(l)
Sec. 25.1355 Distribution system.... ................................... Sec. 25.1719(b)(5)
[[Page 58547]]
Sec. 25.1360 Precautions against ................................... Sec. 25.1719(b)(6)
injury.
Sec. 25.1362 Electrical supplies for ................................... Sec. 25.1719(b)(7)
emergency conditions.
Sec. 25.1365 Electrical appliances, ................................... Sec. 25.1719(b)(8)
motors, and transformers.
Sec. 25.1431 Electronic equipment... (c)................................ Sec. 25.1719(b)(9)
(d)................................ ...................................
Sec. 25.1529 Instructions for ................................... Sec. 25.1739
Continued Airworthiness.
----------------------------------------------------------------------------------------------------------------
Appendix D
The tables below indicate which of the current rules will need
to be changed to accommodate the new certification requirements and
which will remain the same.
Existing Part 25 Requirements Requiring Revision To Support New Proposed Regulations
----------------------------------------------------------------------------------------------------------------
Existing regulation Revision to existing regulation required?
----------------------------------------------------------------------------------------------------------------
Sec. 25.611.............................................. Yes.
Sec. 25.773.............................................. No.
Sec. 25.855.............................................. Yes.
Sec. 25.863.............................................. No.
Sec. 25.869.............................................. Yes.
Sec. 25.899.............................................. No.
Sec. 25.903.............................................. No.
Sec. 25.1165............................................. No.
Sec. 25.1189............................................. No.
Sec. 25.1203............................................. Yes.
Sec. 25.1301............................................. Yes.
Sec. 25.1309............................................. Yes.
Sec. 25.1310............................................. No.
Sec. 25.1316............................................. No.
Sec. 25.1331............................................. No.
Sec. 25.1351............................................. No.
Sec. 25.1353............................................. Yes.
Sec. 25.1355............................................. No.
Sec. 25.1357............................................. Yes.
Sec. 25.1360............................................. No.
Sec. 25.1362............................................. No.
Sec. 25.1365............................................. No.
Sec. 25.1431............................................. No.
Sec. 25.1529............................................. No.
----------------------------------------------------------------------------------------------------------------
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[[Page 58550]]
Discussion of the EWIS Safety Analysis Process as Depicted in
Flowcharts 1 and 2 (Excerpt From Proposed AC 25.17XX, ``Certification
of Electrical Wiring Interconnection Systems on Transport Category
Airplanes'')
The analysis described here is based on a qualitative approach to
assessing EWIS safety as opposed to numerical, probability-based
quantitative analysis. The intent is not to examine each individual
wire and its relation to other wires. Rather, it is to ensure that
there are no hazardous combinations. However, in case the ``top down''
analysis process described in this AC determines that a failure in a
given bundle may lead to a catastrophic failure condition, the
mitigation process may lead to performing a complete analysis of each
wire in the relevant bundle.
The analysis described may be accomplished in conjunction with the
required aircraft system safety assessments of Sec. Sec. 25.1309,
25.671, etc.
The classification of failure conditions is given in Table 1 (found
in the section-by-section discussion of proposed Sec. 25.1705).
There are two flowcharts contained in this appendix:
Flowchart 1 applies to applicants for pre-TC work and for
amended TCs, and STCs when the applicant has all data necessary to
perform the analysis per Flowchart 1. If Flowchart 1 is used for post-
TC modifications the available data must include identification of the
systems in the EWIS under consideration for modification and the system
functions associated with that EWIS.
Flowchart 2 applies to applicants for post-TC
modifications when the applicant cannot identify the systems or systems
functions contained in EWIS under consideration for modification
The analysis process is initiated by a functional hazard analysis
performed at aircraft level identifying catastrophic and hazardous
failure events.
The processes in both Flowcharts 1 and 2 identify two aspects:
physical and functional failures.
Note: For this discussion the following definitions apply:
Validation: Determination that requirements for a product are
sufficiently correct and complete.
Verification: Evaluation to determine that requirements have
been met.
Physical Failure Analysis: Only single common cause events or
failures need to be addressed during the physical failure analysis as
described in this AC and shown on the left hand sides of Flowcharts 1
and 2. The objective of the physical analysis is to protect against
single common cause events or failures that may involve single or
multiple physical failures. Multiple common cause events or failures
need not be addressed.
In relation to physical effects, it should be assumed that wires
are carrying electrical energy and, in the case of an EWIS failure, as
defined in the preceding paragraph, this energy may result in hazardous
or catastrophic effects directly or when combined with other factors
(fuel, oxygen, hydraulic fluid, or damage by passengers, for example).
These failures, for example, may result in fire, smoke, emission of
toxic gases, and damage to co-located systems and structural elements
or injury to personnel. This analysis considers all EWIS from all
systems regardless of criticality, (autopilot, auto throttle, PA
system, IFE system, etc.).
Functional Failure Analysis: The functional failure analysis
assumes that electrical wires are carrying power, signal, or
information data. Failure of EWIS under these circumstances may lead to
aircraft system degradation effects.
Descriptive Text for Flowchart 1
Box A
The functional hazard assessment (FHA) referred to in this box is
not a stand-alone separate document specifically created to show
compliance with Sec. 25.1705. It is the aircraft level FHA that the
applicant will have developed in compliance with Sec. 25.1309 to help
demonstrate acceptability of a design concept, identify potential
problem areas or desirable design changes, or determine the need for
and scope of any additional analyses (refer to AC/ACJ 25.1309-1B).
Physical Failures
Box B
EWIS Characteristics: Use the results of the FHA (BOX A) to
identify EWIS installation criteria and definitions of component
characteristics. Results of BOX B are fed into the preliminary system
safety analysis (PSSA) and system safety analysis (SSA) of BOX J.
Boxes C, D, and E
Validation and Verification of Installation Criteria: Ensure that
the EWIS component qualification satisfies the design requirements and
that components are selected, used, and installed according to their
qualification characteristics and the aircraft constraints linked to
their location.
Using available information (e.g., digital mockup, physical mockup,
aircraft, historical data), inspections and analyses (e.g., 1st article
inspection, design review, particular risks, zonal safety assessments,
zonal inspections, common mode analysis, as applicable) should be
performed to validate that design and installation criteria are
adequate to the zone/function, including multi-systems impact. Also,
the inspections and analyses should be used to assess whether design
and installation criteria were correctly applied. Special consideration
should be given to those areas of the airplane that are known problem
areas based on service history and historical data (e.g., arcing,
smoke, loose clamps, chafing, arc tracking, interference with other
systems, etc.). Special considerations should also be given to cases
where new (previously unused) material or other technologies are used.
Deviations from installation and component selection criteria
identified by these activities should be evaluated and a determination
made about their acceptability. Alternative mitigation strategies
should be developed as necessary.
Boxes F & G
Development and Validation of Mitigation Strategy: Identify and
develop a mitigation strategy for the physical failures and their
adverse effects identified in BOXES D and E.
Validation and verification of the mitigation solution
should ensure that:
Hazardous failure conditions are extremely remote.
Catastrophic failure conditions do not result from a
single common cause event or failure.
This mitigation solution does not introduce any new
potential failure conditions.
Box H
Incorporate newly developed mitigation strategies (BOX F) into
guidelines (BOX B) for further design and inspection and analysis
process.
Box I
From the EWIS physical failure analysis, document the physical
failures that were addressed, their effects, and the mitigation
strategies that were developed. This information supports the final
analysis documentation (BOX P).
Functional Failures
Box J
System Safety Assessment: Use results of the aircraft level FHA
(BOX A) to guide the system level FHA (BOX J).
EWIS failures identified by Sec. 25.1705 are to be incorporated
into the system
[[Page 58551]]
level and aircraft level FHA, as necessary, the PSSA, the common cause
analysis (CCA), and the SSA. These analyses are performed to satisfy
requirements of Sec. 25.1309.
Use results of these analyses to update the EWIS definition (BOX
B).
Boxes K, L, and M
Hazardous and Catastrophic Failure Conditions: Use the analyses in
BOX J to determine if the EWIS associated with the system under
analysis can contribute (in whole or in part) to the failure condition
under study. A determination needs to be made about whether the EWIS
failure needs to be mitigated. If yes, a mitigation strategy needs to
be developed, validated, and verified. If no, the appropriate safety
assessment should be completed (e.g., per Sec. 25.1309, Sec. 25.671,
etc.).
Boxes N and O
Development and Validation of Mitigation Strategy: Identify and
develop a mitigation strategy for the functional failures and adverse
effects identified in BOX J.
Validation and verification of the mitigation solution should
determine if initial objective is fully reached and confirm that this
mitigation solution is compatible with existing installations and
installation criteria. If the EWIS was the failure cause, the
subsequent mitigation strategy developed may introduce new adverse
effects not previously identified by the analysis. A check for any new
adverse effects should be accomplished and the aircraft level FHA and
other system safety assessments should be updated as necessary.
Box P
After the mitigation strategies have been validated and verified,
document the results of the Sec. 25.1705 analysis. Update as necessary
the aircraft level FHA that has been developed in support of
certification of the proposed modification, in compliance with Sec.
25.1309, (BOX A).
Descriptive Text for Flowchart 2
The main objectives are to ensure that the proposed modification
will be correctly designed and installed and will not adversely affect
existing systems.
As far as EWIS is concerned, correct incorporation of the
modification should be ensured by both good knowledge of original
aircraft manufacturer (OAM) installation practices and their correct
implementation or by adequate separation of the added EWIS from
existing EWIS. In either case, physical analyses should be performed
(similar to the physical failures part of Flowchart 1).
Box A
Aircraft level effects must be considered for modified systems or
systems added to the aircraft. If the applicant has the aircraft level
FHA it should be examined to determine the airplane-level effect of the
proposed modification. If the applicant doesn't have the aircraft level
FHA, then the applicant must generate an aircraft level FHA based on
the proposed modification. This aircraft level FHA would be limited to
just those aircraft systems affected by the proposed modification. If
it is determined that no aircraft level functional effects are
introduced, a statement to this effect and the supporting data is
sufficient to satisfy BOX A.
Physical Failures
Box B
EWIS Characteristics: Use results of the aircraft level FHA (BOX A)
to identify EWIS installation criteria and definitions of component
characteristics. Results of BOX B are fed into the PSSA and SSA of BOX
J.
Box C
Separate the EWIS to be added from other existing airplane EWIS
since it cannot be determined what systems or system functions are
contained in the existing EWIS. Physical separation between the new and
existing EWIS must be achieved through separation distance or an
appropriate barrier or other means shown to be at least equivalent to
the physical separation distance when allowed by Sec. 25.1709. Methods
given in the proposed advisory material for Sec. 25.1709 provide an
acceptable way to determine adequate separation.
In cases where separation cannot be maintained because of physical
constraints (e.g., terminal strips and connectors, etc.), the applicant
should accomplish the appropriate analysis to show that no adverse
failure conditions exist because of sharing the common device. This
requires that the applicant have knowledge of the systems or system
functions sharing the common device (e.g. terminal strips and
connectors etc.).
Boxes D and E
Validation and Verification of Installation Criteria
Ensure that the EWIS component qualification satisfies the design
requirements and that components are selected, used, and installed
according to their qualification characteristics and the aircraft
constraints linked to their location.
Using available information (e.g., digital mockup, physical mockup,
aircraft, historical data), inspections and analyses (e.g. 1st article
inspection, design review, particular risks, zonal safety assessments,
zonal inspections, common mode analysis, as applicable) should be
performed to validate that design and installation criteria are
adequate to the zone/function, including multi-systems impact. Also,
inspections and analyses should be used to assess whether design and
installation criteria were correctly applied. Special consideration
should be given to those areas of the airplane that are known problem
areas based on service history and historical data (e.g., arcing,
smoke, loose clamps, chafing, arc tracking, interference with other
systems, etc.). Special consideration should also be given to cases
where new (previously unused) material or other technologies are used.
Deviation from installation and component selection criteria
identified by these activities should be evaluated and a determination
made about their acceptability. Alternative mitigation strategies
should be developed as necessary.
Boxes F and G
Development & Validation of Mitigation Strategy
Identify and develop a mitigation strategy for the physical
failures and their adverse effects identified in Boxes D and E.
Validation and verification of the mitigation solution should
ensure that:
Hazardous failure conditions are extremely remote.
Catastrophic failure conditions do not result from a
single common cause event or failure.
This mitigation solution does not introduce any new
potential failure conditions.
Box H
Incorporate newly developed mitigation strategies (Box F) into
guidelines (Box B) for further design and inspection and analysis
process.
Box I
From the EWIS physical failure analysis, document the physical
failures that were addressed, their effects, and mitigation strategies
that were developed. This information supports the final analysis
documentation (Box P).
[[Page 58552]]
Functional Failures
Box J
System Safety Assessment
Use the results of the aircraft level FHA (Box A) to guide the
system level FHA (Box J).
EWIS failures identified by Sec. 25.1705 are to be incorporated
into the system level and aircraft level FHA, as necessary, the PSSA,
the CCA, and the SSA. These analyses are performed to satisfy
requirements of Sec. 25.1309.
Use results of these analyses to update the EWIS definition (Box
B).
Boxes K, L, and M
Hazardous and Catastrophic Failure Conditions
Use the analyses in Box J to determine if the EWIS associated with
the system under analysis can contribute (in whole or in part) to the
failure condition under study. A determination needs to be made about
whether the EWIS failure needs to be mitigated. If yes, a mitigation
strategy needs to be developed, validated, and verified. If no, the
appropriate safety assessment should be completed (e.g., per Sec.
25.1309, Sec. 25.671, etc.).
Boxes N and O
Development and Validation of Mitigation Strategy
Identify and develop a mitigation strategy for the functional
failures and adverse effects identified in Box J.
Validation and verification of the mitigation solution should
determine if initial objective is fully reached and confirm that this
mitigation solution is compatible with existing installations and
installation criteria. If the EWIS was the failure cause, the
subsequent mitigation strategy developed may introduce new adverse
effects not previously identified by the analysis. A check for any new
adverse effects should be accomplished and the aircraft level FHA and
other system safety assessments should be updated as necessary.
Box P
After the mitigation strategies have been validated and verified,
document the results of the Sec. 25.1705 analysis. Update as necessary
the aircraft level FHA that has been developed in support of
certification of the proposed modification, in compliance with Sec.
25.1309, (Box A).
List of Subjects
14 CFR Part 1
Air Transportation.
14 CFR Parts 25, 91, 125
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
14 CFR Parts 121, 129
Air carriers, Aircraft, Aviation safety, Reporting and
recordkeeping requirements.
The Proposed Amendments
In consideration of the foregoing, the Federal Aviation
Administration proposes to amend Chapter I of Title 14, Code of Federal
Regulations parts 1, 25, 91, 121, 125, and 129 as follows:
PART 1--DEFINITIONS AND ABBREVIATIONS
1. The authority citation for part 1 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
2. Amend Sec. 1.2 to add the following abbreviation in
alphabetical order:
Sec. 1.2 Abbreviations and symbols.
* * * * *
EWIS means electrical wiring interconnection system.
* * * * *
PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES
3. The authority citation for part 25 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702 and 44704.
4. Amend Sec. 25.1 by adding a new paragraph (c) to read as
follows:
Sec. 25.1 Applicability.
* * * * *
(c) This part also establishes requirements for holders of type
certificates and changes to those certificates to take actions
necessary to support the continued airworthiness of transport category
airplanes.
5. Amend Sec. 25.2 by adding a new paragraph (d) to read as
follows:
Sec. 25.2 Special retroactive requirements.
* * * * *
(d) In addition to the requirements of this section, subpart I of
this part contains requirements that apply to--
(1) Holders of type certificates; and
(2) Applicants for type certificates, changes to type certificates
(including service bulletins describing design changes), and
supplemental type certificates.
6. Amend Sec. 25.611 by designating the existing paragraph as
paragraph (a) and adding new paragraph (b) to read as follows:
Sec. 25.611 Accessibility provisions.
(a) * * *
(b) EWIS must meet the accessibility requirements of Sec. 25.1725.
7. Amend Sec. 25.855 by removing the word ``wiring'' from
paragraph (e) introductory text and adding new paragraph (j) as
follows:
Sec. 25.855 Cargo or baggage compartments.
* * * * *
(j) Cargo or baggage compartment electrical wiring interconnection
system components must meet the requirements of Sec. 25.1727.
8. Amend Sec. 25.869 by removing paragraph (a)(4) and revising
paragraphs (a)(2) and (a)(3) as follows:
Sec. 25.869 Fire protection: systems.
(a) * * *
(1) * * *
(2) Equipment that is located in designated fire zones and is used
during emergency procedures must be at least fire resistant.
(3) EWIS components must meet the requirements of Sec. 25.1713.
* * * * *
9. Amend part 25 by adding a new Sec. 25.899 to read as follows:
Sec. 25.899 Electrical bonding and protection against static
electricity.
(a) Electrical bonding and protection against static electricity
must be designed to minimize accumulation of electrostatic charge that
would cause--
(1) Human injury from electrical shock,
(2) Ignition of flammable vapors, or
(3) Interference with installed electrical/electronic equipment.
(b) Compliance with paragraph (a) of this section may be shown by--
(1) Bonding the components properly to the airframe; or
(2) Incorporating other acceptable means to dissipate the static
charge so as not to endanger the airplane, personnel, or operation of
the installed electrical/electronic systems.
10. Amend Sec. 25.1203 by revising paragraph (e) and adding a new
paragraph (h) as follows:
Sec. 25.1203 Fire detector system.
* * * * *
(e) Components of each fire or overheat detector system in a fire
zone must be at least fire-resistant.
* * * * *
(h) EWIS for each fire or overheat detector system in a fire zone
must meet the requirements of Sec. 25.1727.
11. Amend Sec. 25.1301 by designating the introductory text as
paragraph (a), redesignating paragraphs (a) through (d) as (1) through
(4), and adding a new paragraph (b) as follows:
[[Page 58553]]
Sec. 25.1301 Function and installation.
* * * * *
(b) EWIS must meet the requirements of subpart H of this part.
12. Amend Sec. 25.1309 by removing paragraph (e) and redesignating
paragraph (g) as paragraph (e) and revising paragraph (f) as follows:
Sec. 25.1309 Equipment, systems, and installations.
* * * * *
(f) EWIS must be assessed in accordance with the requirements of
Sec. 25.1705.
13. Amend part 25 by adding a new Sec. 25.1310, to read as
follows:
Sec. 25.1310 Power source capacity and distribution.
(a) Each installation whose functioning is required for type
certification or under operating rules and that requires a power supply
is an ``essential load'' on the power supply. The power sources and the
system must be able to supply the following power loads in probable
operating combinations and for probable durations:
(1) Loads connected to the system with the system functioning
normally.
(2) Essential loads, after failure of any one prime mover, power
converter, or energy storage device.
(3) Essential loads after failure of--
(i) Any one engine on two-engine airplanes; and
(ii) Any two engines on three-or-more-engined airplanes.
(4) Essential loads for which an alternate source of power is
required, after any failure or malfunction in any one power supply
system, distribution system, or other utilization system.
(b) In determining compliance with paragraphs (a) (2) and (3) of
this section, the power loads may be assumed to be reduced under a
monitoring procedure consistent with safety in the kinds of operation
authorized. Loads not required in controlled flight need not be
considered for the two-engine-inoperative condition on airplanes with
three or more engines.
14. Amend Sec. 25.1353 by revising paragraphs (a), (b), and (d) as
follows:
Sec. 25.1353 Electrical equipment and installations.
(a) Electrical equipment and controls must be installed so that
operation of any one unit or system of units will not adversely affect
the simultaneous operation of any other electrical unit or system
essential to safe operation. Any electrical interference likely to be
present in the airplane must not result in hazardous effects on the
airplane or its systems.
(b) EWIS components must meet the requirements of Sec. 25.1357,
Sec. 25.1703, Sec. 25.1709, Sec. 25.1711, and Sec. 25.1721.
(c) * * *
(d) Electrical bonding must provide an adequate electrical return
path under both normal and fault conditions, on airplanes having
grounded electrical systems.
15. Amend Sec. 25.1357 by revising paragraphs (d) and (f) to read
as follows:
Sec. 25.1357 Circuit protective devices.
* * * * *
(d) If the ability to reset a circuit breaker or replace a fuse is
essential to safety in flight, that circuit breaker or fuse must be
located and identified so that it can be readily reset or replaced in
flight. Where fuses are used, there must be spare fuses for use in-
flight equal to at least 50% of the number of fuses of each rating
required for complete circuit protection.
* * * * *
(f) For airplane systems for which the ability to remove or reset
power during normal operations is necessary, the system must be
designed so that circuit breakers are not the primary means to remove
or reset system power unless specifically designed for use as a switch.
* * * * *
16. Amend part 25 by adding a new Sec. 25.1360 to read as follows:
Sec. 25.1360 Precautions against injury.
(a) Shock. The electrical system must be designed to minimize risk
of electric shock to crew, passengers, and servicing personnel and to
maintenance personnel using normal precautions.
(b) Burns. The temperature of any part that may be handled by a
crewmember during normal operations must not cause dangerous
inadvertent movement by the crewmember or injury to the crewmember.
17. Amend part 25 by adding a new Sec. 25.1362 to read as follows:
Sec. 25.1362 Electrical supplies for emergency conditions.
A suitable electrical supply must be provided to those services
required for emergency procedures after an emergency landing or
ditching. The circuits for these services must be designed, protected,
and installed so that the risk of their causing a fire under these
emergency conditions is minimized.
18. Amend part 25 by adding a new Sec. 25.1365 to read as follows:
Sec. 25.1365 Electrical appliances, motors, and transformers.
(a) Domestic appliances must be designed and installed so that in
the event of failures of the electrical supply or control system, the
requirements of Sec. 25.1309(b), (c), and (d) will be satisfied.
Domestic appliances are items such as cooktops, ovens, coffee makers,
water heaters, refrigerators, and toilet flush systems that are placed
on the airplane to provide service amenities to passengers.
(b) Galleys and cooking appliances must be installed in a way that
minimizes risk of overheat or fire.
(c) Domestic appliances, particularly those in galley areas, must
be so installed or protected as to prevent damage or contamination of
other equipment or systems from fluids or vapors which may be present
during normal operation or as a result of spillage, if such damage or
contamination may create a hazardous condition.
(d) Unless compliance with Sec. 25.1309(b) is provided by the
circuit protective device required by Sec. 25.1357(a), electric motors
and transformers, including those installed in domestic systems, must
have a suitable thermal protection device to prevent overheating under
normal operation and failure conditions, if overheating would create a
smoke or fire hazard.
19. Amend part 25 by adding new subpart H to read as follows:
Subpart H--Electrical Wiring Interconnection Systems (EWIS)
Sec.
25.1701 Definition.
25.1703 Function and installation: EWIS.
25.1705 System safety: EWIS.
25.1707 [Reserved]
25.1709 System separation: EWIS.
25.1711 Component identification: EWIS.
25.1713 Fire protection: EWIS.
25.1715 [Reserved]
25.1717 Electrical bonding and protection against static
electricity: EWIS.
25.1719 Systems and functions: EWIS.
25.1721 Circuit protective devices: EWIS.
25.1723 Instruments using a power supply: EWIS.
25.1725 Accessibility provisions: EWIS.
25.1727 Protection of EWIS.
25.1729 Flammable fluid fire protection: EWIS.
25.1731 Powerplants: EWIS.
25.1733 Flammable fluid shutoff means: EWIS.
25.1735 Fire detector systems, general: EWIS.
25.1737 Powerplant and APU fire detector system: EWIS.
25.1739 Instructions for Continued Airworthiness: EWIS.
Subpart H--Electrical Wiring Interconnection Systems (EWIS)
Sec. 25.1701 Definition.
(a) As used in this chapter, electrical wiring interconnection
system (EWIS)
[[Page 58554]]
means any wire, wiring device, or combination of these, including
termination devices, installed in any area of the airplane for the
purpose of transmitting electrical energy between two or more intended
termination points. Except as provided for in paragraph (c) of this
section, this includes:
(1) Wires and cables.
(2) Bus bars.
(3) The termination point on electrical devices, including those on
relays, interrupters, switches, contactors, terminal blocks and circuit
breakers, and other circuit protection devices.
(4) Connectors, including feed-through connectors.
(5) Connector accessories.
(6) Electrical grounding and bonding devices and their associated
connections.
(7) Electrical splices.
(8) Materials used to provide additional protection for wires,
including wire insulation, wire sleeving, and conduits that have
electrical termination for the purpose of bonding.
(9) Shields or braids.
(10) Clamps and other devices used to route and support the wire
bundle.
(11) Cable tie devices.
(12) Labels or other means of identification.
(13) Pressure seals.
(b) The definition in paragraph (a) of this section covers EWIS
components inside shelves, panels, racks, junction boxes, distribution
panels, and back-planes of equipment racks, including, but not limited
to, circuit board back-planes and wire integration units.
(c) Except for the equipment indicated in paragraph (b) of this
section, EWIS components inside the following equipment, and the
external connectors that are part of that equipment, are excluded from
the definition in paragraph (a) of this section:
(1) Electrical equipment or avionics that are qualified to
environmental conditions and testing procedures when those conditions
and procedures are-(i)
Appropriate for the intended function and operating environment,
and
(ii) Acceptable to the FAA.
(2) Portable electrical devices that are not part of the type
design of the airplane. This includes personal entertainment devices
and laptop computers.
(3) Fiber optics.
Sec. 25.1703 Function and installation: EWIS.
(a) Each EWIS component installed in any area of the aircraft must:
(1) Be of a kind and design appropriate to its intended function.
(2) Be installed according to limitations specified for the EWIS
components.
(3) Function properly when installed.
(4) Be designed and installed in a way that will minimize
mechanical strain.
(b) Selection of wires must take into account known characteristics
of the wire in relation to each installation and application to
minimize the risk of wire damage, including any arc tracking phenomena.
(c) The design and installation of the main power cables, including
generator cables, must allow for a reasonable degree of deformation and
stretching without failure.
(d) EWIS components located in areas of known moisture accumulation
must be adequately protected to minimize any hazardous effects due to
moisture.
Sec. 25.1705 System safety: EWIS.
Each EWIS must be designed and installed so that:
(a) Each catastrophic failure condition--
(1) Is extremely improbable; and
(2) Does not result from a single failure.
(b) Each hazardous failure condition is extremely remote.
Sec. 25.1707 [Reserved]
Sec. 25.1709 System separation: EWIS.
(a) Each EWIS must be designed and installed so that under normal
conditions and failure conditions as defined by Sec. 25.1309(b)(1) and
(b)(2), it will not adversely affect the simultaneous operation of any
other systems necessary for continued safe flight, landing, and egress.
Unless otherwise stated, for the purposes of this section, adequate
physical separation must be achieved by separation distance or by a
barrier that provides protection equivalent to that separation
distance.
(b) Each EWIS must be designed and installed so that any electrical
interference likely to be present in the airplane will not result in
hazardous effects upon the airplane or its systems.
(c) Wires and cables carrying heavy current, and their associated
EWIS components, must be designed and installed to ensure adequate
physical separation and electrical isolation so that damage to
essential circuits will be minimized under fault conditions.
(d) Each EWIS associated with independent airplane power sources
must be designed and installed to ensure adequate physical separation
and electrical isolation so that a fault in any one airplane power
source EWIS will not adversely affect any other independent power
sources. In addition:
(1) Airplane independent electrical power sources must not share a
common ground terminating location.
(2) Airplane system static grounds must not share a common ground
terminating location with any of the airplane's independent electrical
power sources.
(e) Except to the extent necessary to provide electrical connection
to the fuel systems components, the EWIS must be designed and installed
with adequate physical separation from fuel lines and other fuel system
components, so that:
(1) Any EWIS component failure will not create a hazardous
condition.
(2) Any fuel leakage onto EWIS components will not create a
hazardous condition.
(f) Except to the extent necessary to provide electrical connection
to the hydraulic systems components, EWIS must be designed and
installed with adequate physical separation from hydraulic lines and
other hydraulic system components, so that:
(1) Any EWIS component failure will not create a hazardous
condition.
(2) Any hydraulic fluid leakage onto EWIS components will not
create a hazardous condition.
(g) Except to the extent necessary to provide electrical connection
to the oxygen systems components, EWIS must be designed and installed
with adequate physical separation from oxygen lines and other oxygen
system components, so that any EWIS component failure will not create a
hazardous condition.
(h) Except to the extent necessary to provide electrical connection
to the water/waste systems components, EWIS must be designed and
installed with adequate physical separation from water/waste lines and
other water/waste system components, so that:
(1) Any EWIS component failure will not create a hazardous
condition.
(2) Any water/waste leakage onto EWIS components will not create a
hazardous condition.
(i) EWIS must be designed and installed with adequate physical
separation between the EWIS and flight or other mechanical control
systems cables and associated system components, so that:
(1) Chafing, jamming, or other interference are prevented.
(2) Any EWIS component failure will not create a hazardous
condition.
(3) Failure of any flight or other mechanical control systems
cables or systems components will not damage the EWIS and create a
hazardous condition.
(j) EWIS must be designed and installed with adequate physical
[[Page 58555]]
separation between the EWIS components and heated equipment, hot air
ducts, and lines, so that:
(1) Any EWIS component failure will not create a hazardous
condition.
(2) Any hot air leakage or heat generated onto EWIS components will
not create a hazardous condition.
(k) For systems for which redundancy is required, by certification
rules, by operating rules, or as a result of the assessment required by
Sec. 25.1705, EWIS components associated with those systems must be
designed and installed with adequate physical separation.
(l) Each EWIS must be designed and installed so there is adequate
physical separation between it and aircraft structure, and so that the
EWIS is protected from sharp edges and corners, to minimize potential
for abrasion/chafing, vibration damage, and other types of mechanical
damage.
Sec. 25.1711 Component identification: EWIS.
(a) EWIS components must be labeled or otherwise identified using a
consistent method that facilitates identification of the wire, its
function, and its design limitations, if any.
(b) For systems for which redundancy is required, by certification
rules, by operating rules, or as a result of the assessment required by
Sec. 25.1705, , EWIS components associated with those systems must be
specifically identified with component part number, function, and
separation requirement for bundles.
(1) The identification must be placed along the wire, cable, or
wire bundle at appropriate intervals and in areas of the airplane where
it is readily visible to maintenance, repair, or alteration personnel.
(2) If an EWIS component cannot be marked physically, then other
means of identification must be provided.
(c) The identifying markings required by paragraphs (a) and (b) of
this section must remain legible throughout the expected service life
of the EWIS component.
(d) The means used for identifying each EWIS component as required
by this section must not have an adverse effect on the performance of
that component throughout its expected service life.
(e) Identification for EWIS modifications to the type design must
be consistent with the identification scheme of the original type
design.
Sec. 25.1713 Fire protection: EWIS.
(a) All EWIS components must meet the applicable fire and smoke
protection requirements of Sec. 25.831(c) of this part.
(b) EWIS components that are located in designated fire zones and
are used during emergency procedures must be at least fire resistant.
(c) Insulation on electrical wire and electrical cable, and
materials used to provide additional protection for the wire and cable,
installed in any area of the airplane, must be self-extinguishing when
tested in accordance with the applicable portions of Appendix F, part
I, of 14 CFR part 25.
Sec. 25.1715 [Reserved]
Sec. 25.1717 Electrical bonding and protection against static
electricity: EWIS.
(a) EWIS components used for electrical bonding and protection
against static electricity must meet the requirements of Sec. 25.899.
(b) Electrical bonding provided by EWIS components must provide an
adequate electrical return path under both normal and fault conditions,
on airplanes having grounded electrical systems.
Sec. 25.1719 Systems and functions: EWIS.
(a) EWIS associated with systems required for type certification or
by operating rules must be considered an integral part of that system
and must be considered in showing compliance with the applicable
requirements for that system.
(b) For systems to which the following rules apply, the components
of EWIS associated with those systems must be considered an integral
part of that system or systems and must be considered in showing
compliance with the applicable requirements for that system.
(1) Sec. 25.773(b)(2) Pilot compartment view.
(2) Sec. 25.981 Fuel tank ignition prevention.
(3) Sec. 25.1165 Engine ignition systems.
(4) Sec. 25.1310 Power source capacity and distribution.
(5) Sec. 25.1316 System lightning protection.
(6) Sec. 25.1351 General.
(7) Sec. 25.1355 Distribution system.
(8) Sec. 25.1360 Precautions against injury.
(9) Sec. 25.1362 Electrical supplies for emergency conditions.
(10) Sec. 25.1365 Electrical appliances, motors, and transformers.
(11) Sec. 25.1431(c) and (d) Electronic equipment.
Sec. 25.1721 Circuit protective devices: EWIS.
Electrical wires and cables must be designed and installed so they
are compatible with the circuit protection devices required by Sec.
25.1357, so that a fire or smoke hazard cannot be created under
temporary or continuous fault conditions.
Sec. 25.1723 Instruments using a power supply: EWIS.
EWIS components associated with any instrument required by Sec.
25.1303(b) that uses a power supply must be designed and installed so
that failure of the EWIS components would not affect that instrument's
compliance with Sec. 25.1331(a)(2).
Sec. 25.1725 Accessibility provisions: EWIS.
Access must be provided to allow inspection and replacement of any
EWIS component as necessary for continued airworthiness.
Sec. 25.1727 Protection of EWIS.
(a) No cargo or baggage compartment may contain any EWIS whose
damage or failure may affect safe operation, unless the EWIS is
protected so that:
(1) It cannot be damaged by movement of cargo or baggage in the
compartment.
(2) Its breakage or failure will not create a fire hazard.
(b) EWIS must be designed and installed to minimize damage and risk
of damage to EWIS by movement of people in the airplane during all
phases of flight, maintenance, and servicing.
(c) EWIS must be designed and installed to minimize damage and risk
of damage to EWIS by items carried onto the aircraft by passengers or
cabin crew.
Sec. 25.1729 Flammable fluid fire protection: EWIS.
EWIS components located in each area where flammable fluid or
vapors might escape by leakage of a fluid system must be considered to
be a potential ignition source and must meet the requirements of Sec.
25.863.
Sec. 25.1731 Powerplants: EWIS.
(a) EWIS associated with any powerplant must be designed and
installed so that the failure of an EWIS component will not prevent the
continued safe operation of the remaining powerplants or require
immediate action by any crewmember for continued safe operation, in
accordance with the requirements of Sec. 25.903(b).
(b) Design precautions must be taken to minimize hazards to the
airplane due to EWIS damage in the event of a powerplant rotor failure
or a fire originating within the powerplant that burns through the
powerplant case, in accordance with the requirements of Sec.
25.903(d)(1).
Sec. 25.1733 Flammable fluid shutoff means: EWIS.
EWIS associated with each flammable fluid shutoff means and control
must be fireproof or must be located and
[[Page 58556]]
protected so that any fire in a fire zone will not affect operation of
the flammable fluid shutoff means, in accordance with the requirements
of Sec. 25.1189.
Sec. 25.1735 Fire detector systems, general: EWIS.
EWIS associated with any installed fire protection system must be
considered an integral part of the system in showing compliance with
the applicable requirements for that system.
Sec. 25.1737 Powerplant and APU fire detector system: EWIS.
(a) EWIS that are part of each fire or overheat detector system in
a fire zone must be at least fire-resistant.
(b) No EWIS component of any fire or overheat detector system for
any fire zone may pass through another fire zone, unless:
(1) It is protected against the possibility of false warnings
resulting from fires in zones through which it passes; or
(2) Each zone involved is simultaneously protected by the same
detector and extinguishing system.
(c) EWIS that are part of each fire or overheat detector system in
a fire zone must meet the requirements of Sec. 25.1203.
Sec. 25.1739 Instructions for Continued Airworthiness: EWIS.
The applicant must prepare Instructions for Continued Airworthiness
applicable to EWIS in accordance with Appendix H sections H25.4 and
H25.5 to this part that are approved by the FAA.
20. Amend part 25 by adding new subpart I to read as follows.
Subpart I--Continued Airworthiness and Safety Improvements
Sec.
25.1801 Purpose and definition.
25.1803 [Reserved]
25.1805 Electrical wiring interconnection systems (EWIS) maintenance
program.
Subpart I--Continued Airworthiness and Safety Improvements
Sec. 25.1801 Purpose and definition.
(a) This subpart establishes requirements for support of the
continued airworthiness of transport category airplanes. These
requirements may include performing assessments, developing design
changes, developing revisions to Instructions for Continued
Airworthiness, and making necessary documentation available to affected
persons. This subpart applies to the following persons, as specified in
each section of this subpart:
(1) Holders of type certificates.
(2) Applicants for type certificates and changes to type
certificates (including service bulletins describing design changes).
Applicants for changes to type certificates must comply with the
requirements of this subpart in addition to the airworthiness
requirements determined applicable under Sec. 21.101 of this
subchapter.
(b) For purposes of this subpart, the ``FAA Oversight Office'' is
the aircraft certification office or office of the Transport Airplane
Directorate with oversight responsibility for the relevant type
certificate or supplemental type certificate, as determined by the
Administrator.
Sec. 25.1803 [Reserved]
Sec. 25.1805 Electrical wiring interconnection systems (EWIS)
maintenance program.
(a) Except as provided in paragraph (f) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of the
original certification, or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more or
(2) A maximum payload capacity of 7,500 pounds or more.
(b) Each person identified in paragraph (c) of this section must
develop and submit for review and approval by the FAA Oversight Office
Instructions for Continued Airworthiness for the representative
airplane's EWIS in accordance with Appendix H paragraphs H25.5(a)(1)
and (b) of this part in effect on [effective date of final rule] for
each affected type design. For purposes of this section, the
``representative airplane'' is the configuration of each model series
airplane that incorporates all variations of EWIS used on that series
airplane, and that includes all TC-holder-designed modifications
mandated by airworthiness directive as of the effective date of this
rule. Each person specified in paragraph (c) of this section must also
review any fuel tank system Instructions for Continued Airworthiness
developed by that person to comply with SFAR 88 to ensure compatibility
with the EWIS Instructions for Continued Airworthiness, including
minimizing redundant requirements.
(c) The following persons must comply with the requirements of
paragraph (b) of this section before the dates specified.
(1) Holders of type certificates (TC): December 16, 2007.
(2) Applicants for TCs, and amendments to TCs (including service
bulletins describing design changes), if the date of application was
before [effective date of final rule] and the certificate was issued on
or after [effective date of final rule]: December 16, 2007, or the date
the certificate is issued, whichever occurs later.
(3) Unless compliance with Sec. 25.1739 of this part is required
or elected, applicants for amendments to TCs, if the application was
filed after [effective date of final rule]: December 16, 2007, or the
date of approval of the application, whichever occurs later.
(4) Applicants for supplemental type certificates (STC), if the
date of application was before [effective date of final rule] and the
certificate was issued on or after [effective date of final rule]: June
16, 2008, or the date of approval of the application, whichever occurs
later.
(5) Unless compliance with Sec. 25.1739 of this part is required
or elected, applicants for STCs, if the application was filed after
[effective date of final rule]: June 16, 2008, or the date of approval
of the application, whichever occurs later.
(d) Each person identified in paragraphs (c)(1), (c)(2), and (c)(4)
of this section must submit to the FAA Oversight Office for approval a
compliance plan by [insert date 90 days after effective date of final
rule]. The compliance plan must include the following information:
(1) A proposed project schedule, identifying all major milestones,
for meeting the compliance dates specified in paragraph (c) of this
section.
(2) A proposed means of compliance with this section, identifying
all required submissions, including all compliance items as mandated in
Appendix H paragraphs H25.5(a)(1) and (b) of this part in effect on
[effective date of this final rule], and all data to be developed to
substantiate compliance.
(3) If the affected person proposes a means of compliance that
differs from that described in FAA advisory material, a detailed
explanation of how the proposed means will be shown to comply with this
section.
(4) A proposal for submitting a draft of all compliance items
required by paragraph (d)(2) of this section for review by the FAA
Oversight Office not less than 60 days before the compliance time
specified in paragraph (c) of this section.
(5) A proposal for how the approved Instructions for Continued
Airworthiness will be made available to affected persons.
(e) Each affected person must implement the compliance plan as
approved in compliance with paragraph
[[Page 58557]]
(d) of this section. If either paragraph (e)(1) or (2) of this section
applies, the affected person must submit a corrected plan to the FAA
Oversight Office and implement the corrected plan within 30 days after
such notification.
(1) The FAA Oversight Office notifies the affected person of
deficiencies in the proposed compliance plan and how to correct them.
(2) The FAA Oversight Office notifies the affected person of
deficiencies in the person's implementation of the plan and how to
correct them.
(f) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
APPENDIX H TO PART 25--INSTRUCTIONS FOR CONTINUED AIRWORTHINESS
21. Amend H25.1 by revising paragraph (a) to read as follows:
H25.1 General.
(a) This appendix specifies requirements for preparation of
Instructions for Continued Airworthiness as required by Sec. Sec.
25.1529, 25.1739, and applicable provisions of subpart I of this
part.
* * * * *
22. Amend H25.4 by revising paragraph (a)(1) and adding new
paragraph (a)(3) to read as follows:
H25.4 Airworthiness Limitations section.
(a) * * *
(1) Each mandatory replacement time, structural inspection
interval, and related structural inspection procedures approved
under Sec. 25.571.
(2) * * *
(3) Any mandatory replacement time of EWIS components as defined
in section 25.1701.
* * * * *
23. Amend Appendix H to part 25 by adding new paragraph H25.5 to
read as follows:
H25.5 Electrical Wiring Interconnection System (EWIS) Instructions for
Continued Airworthiness.
(a) The applicant must prepare Instructions for Continued
Airworthiness applicable to EWIS as defined by Sec. 25.1701 that
are approved by the FAA and include the following:
(1) Maintenance and inspection requirements for the EWIS
developed with the use of an enhanced zonal analysis procedure that
includes:
(i) Identification of each zone of the airplane.
(ii) Identification of each zone that contains EWIS.
(iii) Identification of each zone containing EWIS that also
contains combustible materials.
(iv) Identification of each zone in which EWIS is in close
proximity to both primary and back-up hydraulic, mechanical, or
electrical flight controls and lines.
(v) Identification of--
(A) Tasks, and the intervals for performing those tasks, that
will reduce the likelihood of ignition sources and accumulation of
combustible material, and
(B) Procedures, and the intervals for performing those
procedures, that will effectively clean the EWIS components of
combustible material if there is not an effective task to reduce the
likelihood of combustible material accumulation.
(vi) Instructions for protections and caution information that
will minimize contamination and accidental damage to EWIS, as
applicable, during performance of maintenance, alteration, or
repairs.
(2) Acceptable EWIS maintenance practices in a standard format.
(3) Wire separation requirements as determined under Sec.
25.1709.
(4) Information explaining the EWIS identification method and
requirements for identifying any changes to EWIS under Sec.
25.1711.
(5) Electrical load data and instructions for updating that
data.
(b) The Instructions for Continued Airworthiness must be in the
form of a document appropriate for the information to be provided,
and they must be easily recognizable as EWIS Instructions for
Continued Airworthiness.
PART 91--GENERAL OPERATING AND FLIGHT RULES
24. The authority for part 91 continues to read as follows:
Authority: 49 U.S.C. 106(g), 1155, 40103, 40113, 40120, 44101,
44111, 44701, 44709, 44711, 44712, 44715, 44716, 44717, 44722,
46306, 46315, 46316, 46504, 46506-46507, 47122, 47508, 47528-47531,
articles 12 and 29 of the Convention on International Civil Aviation
(61 stat. 1180).
25. Amend part 91 by adding new Subpart L as follows:
Subpart L--Continued Airworthiness and Safety Improvements
Sec.
91.1501 Purpose and definition.
91.1503 [Reserved]
91.1505 [Reserved]
91.1507 Fuel tank system maintenance program.
Subpart L--Continued Airworthiness and Safety Improvements
Sec. 91.1501 Purpose and definition.
(a) This subpart requires operators to support the continued
airworthiness of each airplane. These requirements may include, but are
not limited to, revising the inspection program, incorporating design
changes, and incorporating revisions to Instructions for Continued
Airworthiness.
(b) For purposes of this subpart, the ``FAA Oversight Office'' is
the aircraft certification office or office of the Transport Airplane
Directorate with oversight responsibility for the relevant type
certificate or supplemental type certificate, as determined by the
Administrator.
Sec. 91.1503 [Reserved]
Sec. 91.1505 [Reserved]
Sec. 91.1507 Fuel tank system maintenance program.
(a) Except as provided in paragraph (g) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
original type certification or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more,
or
(2) A maximum payload capacity of 7,500 pounds or more.
(b) For each airplane on which an auxiliary fuel tank is installed
under a field approval, before December 16, 2007, the operator must
submit to the FAA Oversight Office proposed maintenance instructions
for the tank that meet the requirements of Special Federal Aviation
Regulation No. 88 (SFAR 88) of this chapter.
(c) After December 16, 2008, no operator may operate an airplane
identified in paragraph (a) of this section unless the inspection
program for that airplane has been revised to include inspections,
procedures, and limitations for fuel tank systems.
(d) The proposed fuel tank system inspection program revisions must
be based on the following documents:
(1) The applicable type-certificate-holder-developed fuel tank
Instructions for Continued Airworthiness, developed under SFAR 88, or
under Sec. 25.1529 in
[[Page 58558]]
effect on June 6, 2001, approved by the FAA Oversight Office.
(2) The applicable supplemental-type-certificate-holder-developed
fuel tank Instructions for Continued Airworthiness, if any, developed
under SFAR 88, or Instructions for Continued Airworthiness developed in
accordance with Sec. 25.1529 in effect on June 6, 2001, approved by
the FAA Oversight Office.
(3) The applicable operator-developed inspection instructions for
field-approved auxiliary fuel tanks, if any, approved by the FAA
Oversight Office for the type certificate.
(e) After December 16, 2008, before returning an airplane to
service after any alterations for which fuel tank Instructions for
Continued Airworthiness are developed under SFAR 88, or under Sec.
25.1529 in effect on June 6, 2001, the operator must include in the
inspection program for the airplane inspections and procedures for the
fuel tank system based on those Instructions for Continued
Airworthiness.
(f) The fuel tank system inspection program changes identified in
paragraphs (d) and (e) of this section and any later fuel tank system
revisions must be submitted to the cognizant Flight Standards District
Office (FSDO) for review and approval.
(g) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
26. Designate the text of current Sec. 91.410 as new Sec.
91.1505, removing and reserving paragraph (b), and revising the section
heading to read as follows:
Sec. 91.1505 Repairs assessment for pressurized fuselages.
Sec. 91.410 [Reserved]
27. Sec. 91.410 is reserved.
PART 121--OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL
OPERATIONS
28. The authority citation for part 121 continues to read:
Authority: 49 U.S.C. 106(g), 40113, 40119, 41706, 44101, 44701-
44702, 44705, 44709-44711, 44713, 44716-44717, 44722, 44901, 44903-
44904, 44912, 45101-45105, 46105, 46301.
29. Amend part 121 by adding new subpart Y to read as follows:
Subpart Y--Continued Airworthiness and Safety Improvements
Sec.
121.901 Purpose and definition.
121.903 [Reserved]
121.905 [Reserved]
121.907 [Reserved]
121.909 [Reserved]
121.911 Electrical wiring interconnection systems (EWIS) maintenance
program.
121.913 Fuel tank system maintenance program.
Subpart Y--Continued Airworthiness and Safety Improvements
Sec. 121.901 Purpose and definition.
(a) This subpart requires persons holding an air carrier or
operating certificate under part 119 of this chapter to support the
continued airworthiness of each airplane. These requirements may
include, but are not limited to, revising the maintenance program,
incorporating design changes, and incorporating revisions to
Instructions for Continued Airworthiness.
(b) For purposes of this subpart, the ``FAA Oversight Office'' is
the aircraft certification office or office of the Transport Airplane
Directorate with oversight responsibility for the relevant type
certificate or supplemental type certificate, as determined by the
Administrator.
Sec. 121.903 [Reserved]
Sec. 121.905 [Reserved]
Sec. 121.907 [Reserved]
Sec. 121.909 [Reserved]
Sec. 121.911 Electrical wiring interconnection systems (EWIS)
maintenance program.
(a) Except as provided in paragraph (f) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
original type certification or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more,
or
(2) A maximum payload capacity of 7500 pounds or more.
(b) After December 16, 2008, no certificate holder may operate an
airplane identified in paragraph (a) of this section unless the
maintenance program for that airplane includes inspections and
procedures for electrical wiring interconnection systems (EWIS).
(c) The proposed EWIS maintenance program changes must be based on
the following documents:
(1) The applicable EWIS Instructions for Continued Airworthiness,
developed by the type certificate holder and approved by the FAA
Oversight Office.
(2) The applicable EWIS Instructions for Continued Airworthiness,
if any, developed for supplemental type certificates, approved by the
FAA Oversight Office.
(d) After December 16, 2008, before returning an airplane to
service after any alterations for which EWIS Instructions for Continued
Airworthiness are developed, the certificate holder must include in the
airplane's maintenance program inspections and procedures for EWIS
based on those Instructions for Continued Airworthiness.
(e) The EWIS maintenance program changes identified in paragraphs
(c) and (d) of this section and any later EWIS revisions must be
submitted to the Principal Inspector for review and approval.
(f) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
Sec. 121.913 Fuel tank system maintenance program.
(a) Except as provided in paragraph (g) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
original type certification or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more,
or
(2) A maximum payload capacity of 7500 pounds or more.
(b) For each airplane on which an auxiliary fuel tank is installed
under a
[[Page 58559]]
field approval, before December 16, 2007, the certificate holder must
submit to the FAA Oversight Office proposed maintenance instructions
for the tank that meet the requirements of Special Federal Aviation
Regulation No. 88 (SFAR 88) of this chapter.
(c) After December 16, 2008, no certificate holder may operate an
airplane identified in paragraph (a) of this section unless the
maintenance program for that airplane has been revised to include
inspections, procedures, and limitations for fuel tanks systems.
(d) The proposed fuel tank system maintenance program revisions
must be based on the following documents:
(1) The applicable type-certificate-holder-developed fuel tank
Instructions for Continued Airworthiness, developed under SFAR 88 or
under Sec. 25.1529 in effect on June 6, 2001, approved by the FAA
Oversight Office.
(2) The applicable supplemental-type-certificate-holder-developed
fuel tank Instructions for Continued Airworthiness, if any, developed
under SFAR 88, or under Sec. 25.1529 in effect on June 6, 2001,
approved by the FAA Oversight Office.
(3) The applicable certificate-holder-developed maintenance
instructions for field-approved auxiliary fuel tanks, if any, approved
by the FAA Oversight Office for the type certificate.
(e) After December 16, 2008, before returning an aircraft to
service after any alteration for which fuel tank Instructions for
Continued Airworthiness are developed under SFAR 88 or under Sec.
25.1529 in effect on June 6, 2001, the certificate holder must include
in the maintenance program for the airplane inspections and procedures
for the fuel tank system based on those Instructions for Continued
Airworthiness.
(f) The fuel tank system program changes identified in paragraphs
(d) and (e) of this section and any later fuel tank system revisions
must be submitted to the Principal Inspector for review and approval.
(g) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
Sec. 121.368 [Redesignated as Sec. 121.905]
30. Redesignate Sec. 121.368 as new Sec. 121.905 and reserve
Sec. 121.368.
Sec. 121.368 [Reserved]
31. Sec. 121.368 is reserved.
32. Designate the text of current Sec. 121.370 as new Sec.
121.907, removing and reserving paragraph (b), and revising the section
heading to read as follows:
Sec. 121.907 Repairs assessment for pressurized fuselages.
Sec. 121.370 [Reserved]
33. Sec. 121.370 is reserved.
Sec. 121.370a [Redesignated as Sec. 121.909]
34. Redesignate Sec. 121.370a as new Sec. 121.909 and reserve
Sec. 121.370a.
Sec. 121.370a [Reserved]
35. Sec. 121.370a is reserved.
PART 125--CERTIFICATION AND OPERATIONS: AIRPLANES HAVING A SEATING
CAPACITY OF 20 OR MORE PASSENGERS OR A MAXIMUM PAYLOAD CAPACITY OF
6,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH
AIRCRAFT
36. The authority citation for part 125 continues to read:
Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44705, 44710-
44711, 44713, 44716-44717, 44722.
37. Amend part 125 by adding new subpart M to read as follows:
Subpart M--Continued Airworthiness and Safety Improvements
Sec.
125.501 Purpose and definition.
125.503 [Reserved]
125.505 [Reserved]
125.507 Fuel tank system inspection program.
Subpart M--Continued Airworthiness and Safety Improvements
Sec. 125.501 Purpose and definition.
(a) This subpart requires operators to support the continued
airworthiness of each airplane. These requirements may include, but are
not limited to, revising the inspection program, incorporating design
changes, and incorporating revisions to Instructions for Continued
Airworthiness.
(b) For purposes of this subpart, the ``FAA Oversight Office'' is
the aircraft certification office or office of the Transport Airplane
Directorate with oversight responsibility for the relevant type
certificate or supplemental type certificate, as determined by the
Administrator.
Sec. 125.503 [Reserved]
Sec. 125.505 [Reserved]
Sec. 125.507 Fuel tank system inspection program.
(a) Except as provided in paragraph (g) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
original type certification or later increase in capacity, have--
(1) a maximum type-certificated passenger capacity of 30 or more,
or
(2) a maximum payload capacity of 7500 pounds or more.
(b) For each airplane on which an auxiliary fuel tank is installed
under a field approval, before December 16, 2007, the certificate
holder must submit to the FAA Oversight Office proposed maintenance
instructions for the tank that meet the requirements of Special Federal
Aviation Regulation No. 88 (SFAR 88) of this chapter.
(c) After December 16, 2008, no certificate holder may operate an
airplane identified in paragraph (a) of this section unless the
inspection program for that airplane has been revised to include
inspections, procedures, and limitations for fuel tank systems.
(d) The proposed fuel tank system inspection program revisions must
be based on the following documents:
(1) The applicable type-certificate-holder-developed fuel tank
Instructions for Continued Airworthiness, developed under SFAR 88, or
under Sec. 25.1529 in effect on June 6, 2001, approved by the FAA
Oversight Office.
(2) The applicable supplemental-type-certificate-holder-developed
fuel tank Instructions for Continued Airworthiness, if any, developed
under SFAR 88, or under Sec. 25.1529 in effect on June 6, 2001,
approved by the FAA Oversight Office.
(3) The applicable certificate-holder-developed inspection
instructions for field-approved auxiliary fuel tanks, if any, approved
by the FAA Oversight Office for the type certificate.
(e) After December 16, 2008, before returning an aircraft to
service after any alteration for which fuel tank Instructions for
Continued Airworthiness are developed under SFAR 88, or under Sec.
25.1529 in effect on June 6, 2001, the certificate holder must include
in the inspection program for
[[Page 58560]]
the airplane inspections and procedures for the fuel tank system based
on those Instructions for Continued Airworthiness.
(f) The fuel tank system program changes identified in paragraphs
(d) and (e) of this section and any later fuel tank system revisions
must be submitted to the Principal Inspector for review and approval.
(g) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
38. Designate the text of current Sec. 125.248 as new Sec.
125.505, removing and reserving paragraph (b), and revising the section
heading to read as follows:
Sec. 125.505 Repairs assessment for pressurized fuselages.
Sec. 125.248 [Reserved]
39. Sec. 125.248 is reserved.
PART 129--OPERATIONS: FOREIGN AIR CARRIERS AND FOREIGN OPERATORS OF
U.S.-REGISTERED AIRCRAFT ENGAGED IN COMMON CARRIAGE
40. The authority citation for part 129 continues to read:
Authority: 49 U.S.C. 1372, 40113, 40119, 44101, 44701-44702,
44705, 44709-44711, 44713, 44716-44717, 44722, 44901-44904, 44906,
44912, 46105, Pub. L. 107-71 sec. 104.
41. Amend part 129 by:
A. Designating the existing sections, except Sec. Sec. 129.16,
129.32, and 129.33, as ``Subpart A--General'';
B. Revising paragraph (b) of Sec. 129.1;
C. Redesignating Sec. Sec. 129.16, 129.32, and 129.33 as
Sec. Sec. 129.109, 129.107, and 129.105, respectively, and revising
the heading for newly designated Sec. 129.107 and removing and
reserving paragraph (b); and
D. Adding a new subpart B.
The revisions and additions read as follows:
Subpart A--General
Sec. 129.1 Applicability and definitions.
* * * * *
(b) Operations of U.S.-registered aircraft solely outside the
United States. In addition to the operations specified under paragraph
(a) of this section, Sec. Sec. 129.14 and 129.20 and subpart B of this
part also apply to U.S.-registered aircraft operated solely outside the
United States in common carriage by a foreign person or foreign air
carrier.
* * * * *
Subpart B--Continued Airworthiness and Safety Improvements
Sec.
129.101 Purpose and definition.
129.103 [Reserved]
129.105 Aging airplane inspections and records reviews for U.S.-
registered multiengine aircraft.
129.107 Repairs assessment for pressurized fuselages.
129.109 Supplemental inspections for U.S.-registered aircraft.
129.111 Electrical wiring interconnection systems (EWIS) maintenance
program.
129.113 Fuel tank system maintenance program.
Subpart B--Continued Airworthiness and Safety Improvements
Sec. 129.101 Purpose and definition.
(a) This subpart requires a foreign person or foreign air carrier
operating a U.S. registered airplane in common carriage to support the
continued airworthiness of each airplane. These requirements may
include, but are not limited to, revising the maintenance program,
incorporating design changes, and incorporating revisions to
Instructions for Continued Airworthiness.
(b) For purposes of this subpart, the ``FAA Oversight Office'' is
the aircraft certification office or office of the Transport Airplane
Directorate with oversight responsibility for the relevant type
certificate or supplemental type certificate, as determined by the
Administrator.
Sec. 129.103 [Reserved]
Sec. 129.105 [Redesignated from Sec. 129.33]
Sec. 129.107 [Redesignated from Sec. 129.32]
Sec. 129.109 [Redesignated from Sec. 129.16]
Sec. 129.111 Electrical wiring interconnection systems (EWIS)
maintenance program.
(a) Except as provided in paragraph (f) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
original type certification or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more,
or
(2) A maximum payload capacity of 7500 pounds or more.
(b) After December 16, 2008, no foreign person or foreign air
carrier may operate an airplane identified in paragraph (a) of this
section unless the maintenance program for that airplane includes
inspections and procedures for EWIS.
(c) The proposed EWIS maintenance program changes must be based on
the following documents:
(1) The applicable EWIS Instructions for Continued Airworthiness,
developed by the type certificate holder and approved by the FAA
Oversight Office.
(2) The applicable EWIS Instructions for Continued Airworthiness,
if any, developed for supplemental type certificates, approved by the
FAA Oversight Office.
(d) After December 16, 2008, before returning an airplane to
service after any alterations for which EWIS Instructions for Continued
Airworthiness are developed, the foreign person or foreign air carrier
must include in the maintenance program for that airplane inspections
and procedures for EWIS based on those Instructions for Continued
Airworthiness.
(e) The EWIS maintenance program changes identified in paragraphs
(c) and (d) of this section and any later EWIS revisions must be
submitted to the Principal Inspector or cognizant Flight Standards
International Field Office for review and approval.
(f) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault-Breguet Aviation Mercure 100C
(15) Airbus Caravelle
Sec. 129.113 Fuel tank system maintenance program.
(a) Except as provided in paragraph (g) of this section, this
section applies to transport category, turbine-powered airplanes with a
type certificate issued after January 1, 1958, that, as a result of
[[Page 58561]]
original type certification or later increase in capacity, have--
(1) A maximum type-certificated passenger capacity of 30 or more,
or
(2) A maximum payload capacity of 7500 pounds or more.
(b): For each airplane on which an auxiliary fuel tank is installed
under a field approval, before December 16, 2007, the foreign person or
foreign air carrier operating the airplane must submit to the FAA
Oversight Office proposed maintenance instructions for the tank that
meet the requirements of Special Federal Aviation Regulation No. 88
(SFAR 88) of this chapter.
(c) After December 16, 2008, no foreign person or foreign air
carrier may operate an airplane identified in paragraph (a) of this
section unless the maintenance program for that airplane has been
revised to include inspections, procedures, and limitations for fuel
tanks systems.
(d) The proposed fuel tank system maintenance program revisions
must be based on the following documents:
(1) The applicable type-certificate-holder-developed fuel tank
Instructions for Continued Airworthiness, developed under SFAR 88, or
under Sec. 25.1529 in effect on June 6, 2001, approved by the FAA
Oversight Office.
(2) The applicable supplemental-type-certificate-holder-developed
fuel tank Instructions for Continued Airworthiness, if any, developed
under SFAR 88, or Instructions for Continued Airworthiness developed in
accordance with Sec. 25.1529 in effect on June 6, 2001, approved by
the FAA Oversight Office.
(3) The applicable maintenance instructions for field-approved
auxiliary fuel tanks, if any, developed by the foreign person or
foreign air carrier operating the airplane and approved by the FAA
Oversight Office for the type certificate.
(e) After December 16, 2008, before returning an airplane to
service after any alteration for which fuel tank Instructions for
Continued Airworthiness are developed under SFAR 88, or under Sec.
25.1529 in effect on June 6, 2001, the foreign person or foreign air
carrier must include in the maintenance program for the airplane
inspections and procedures for the fuel tank system based on those
Instructions for Continued Airworthiness.
(f) The fuel tank system program changes identified in paragraphs
(d) and (e) of this section and any later fuel tank system revisions
must be submitted to the Principal Inspector or cognizant Flight
Standards International Field Office for review and approval.
(g) This section does not apply to the following airplane models:
(1) Convair CV-240, 340, 440, if modified to include turbine
engines.
(2) Lockheed L-188
(3) Vickers Armstrong Viscount
(4) Douglas DC-3, if modified to include turbine engines
(5) Bombardier CL-44
(6) Mitsubishi YS-11
(7) British Aerospace BAC 1-11
(8) Concorde
(9) deHavilland D.H. 106 Comet 4C
(10) VFW-Vereinigte Flugtechnische Werk VFW-614
(11) Illyushin Aviation IL 96T
(12) Bristol Aircraft Britannia 305
(13) Handley Page Herald Type 300
(14) Avions Marcel Dassault--Breguet Aviation Mercure 100C
(15) Airbus Caravelle
Issued in Washington, DC on September 22, 2005.
James J. Ballough,
Director, Flight Standards Service.
John J. Hickey,
Director, Aircraft Certification Service.
[FR Doc. 05-19419 Filed 10-5-05; 8:45 am]
BILLING CODE 4910-13-P