[Federal Register Volume 59, Number 249 (Thursday, December 29, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-31903]
[[Page Unknown]]
[Federal Register: December 29, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-SW-03-AD; Amendment 39-9112; AD 95-01-01]
Airworthiness Directives; Terra Corporation TRT 250 Series
Transponders
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to Terra Corporation TRT 250 series transponders, that
requires removing the transponder from the aircraft, inspecting it to
determine if the AD applies, and replacing any affected transponder
with a modified Terra Corporation transponder or another transponder
that responds properly to Mode S interrogations from both an Air
Traffic Control Radio Beacon System (ATCRBS)/Mode S ground station and
Traffic Collision Avoidance System (TCAS) II airborne equipment. This
amendment is prompted by FAA tests that show that the transponder does
not respond properly to certain interrogations by a Mode S or TCAS II
signal. The actions specified by this AD are intended to prevent
failure of the transponder to respond properly to Mode S interrogations
from both Mode S ground stations and TCAS II airborne equipment, which
could result in loss of airspace separation.
DATES: Effective February 6, 1995.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of February 6, 1995.
ADDRESSES: The service information referenced in this AD may be
obtained from Terra Corporation, 3520 Pan American Freeway NE,
Albuquerque, New Mexico, 87107-4796. This information may be examined
at the FAA, Office of the Assistant Chief Counsel, 2601 Meacham Blvd.,
Room 663, Fort Worth, Texas; or at the Office of the Federal Register,
800 North Capitol Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Mr. George R. Hash, Aerospace
Engineer, Airplane Certification Office, FAA, Rotorcraft Directorate,
2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5134,
fax (817) 222-5959.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to Terra Corporation TRT 250 series
transponders was published in the Federal Register on May 26, 1994 (59
FR 27249). The original comment period was open for 30 days. However,
subsequently, the FAA determined that the original comment period was
inadequate and reopened the comment period on September 6, 1994 (59 FR
46007) with no additional changes in the proposed rule. That action
proposed to require removing the transponder from the aircraft,
inspecting it to determine if the AD applies, and replacing any
affected transponder with a modified Terra Corporation transponder or
another transponder that responds properly to Mode S interrogations
from both an ATCRBS/Mode S ground station and TCAS II airborne
equipment.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Thirty-four comments were received
from thirty-one commenters. Three of the commenters responded twice and
two commenters commented on two different items contained in the Notice
of Proposed Rulemaking (NPRM). Due consideration has been given to the
comments received. Two commenters request that certain information be
included in the preamble language that further explains the history
behind these transponders and this AD. These commenters request that
language be inserted in the final rule stating that: (1) these
transponders have been produced since 1985; (2) these transponders meet
the requirements of Technical Service Order (TSO)-C74c; (3) the Mode S
ground stations and the TCAS II airborne equipment interrogates beyond
the ATCRBS interrogation for which these transponders were designed
instead of stating that the Mode S and TCAS II interrogates beyond the
P3 pulse; and (4) the economic analysis that shows the $298 as the
cost of the required parts not only includes the cost of the parts, but
also the labor required to modify the affected transponders. While the
FAA agrees with the substance of these comments, they are not proposing
any changes to the AD language; therefore, no changes are made to the
AD based upon these comments.
Four commenters state that this AD should be published as an
immediately adopted final rule because of its serious safety
implications. The FAA does not concur. The FAA determined that, based
upon the impact of the proposed requirements of this AD, it was
appropriate to acquire as many public comments as possible prior to
finalizing the actions. Therefore, the FAA published an NPRM soliciting
public comments. To ensure the safety of flight, the Mode S ground
stations are temporarily altered to permit the affected transponders to
respond properly to ATCRBS interrogations during the compliance period.
Another two commenters state that there is no justification for an
extended compliance period and that compliance should be required as
soon as possible. The FAA does not concur that a compliance time of
less than 6 months is appropriate. With an estimated 5,000 transponders
in the field that require replacement or modification, a compliance
time of less than 6 months would not allow adequate time for all
transponders to be modified or replaced.
Two commenters state that longer compliance times should be
provided within which to modify these transponders because no
significant safety hazard exists. The FAA does not concur. In April
1994, Terra Corporation notified its customers of the forthcoming FAA
AD against the TRT 250 series transponders. The FAA informed the public
via the NPRM process in May 1994, and provided a 30-day comment period.
The comment period for the NPRM was reopened in September 1994 to
provide another 60 days for additional comments. Public notices
appeared in several aviation trade publications during this period. The
manufacturer indicates that several hundred transponders have been
modified since the May 1994 publication of the NPRM. Transport aircraft
that utilize TCAS II and Mode S transponders cannot detect those
aircraft equipped with a Terra transponder built according to the
requirements of TSO-C74c. As a direct result of the Terra transponder
problem, a thorough evaluation and a complete implementation of Mode S
ground sensors cannot occur until the transponders are modified. In
summary, this AD establishes the existence of an aviation safety
problem, and the FAA has allowed an appropriate compliance time for
action by owners or operators.
One commenter states that the FAA employee or employees involved
with the approval of the original transponder's design should pay for
the costs of modifying the transponders. The FAA does not concur. The
FAA as an agency is responsible for all directives, policies, mandates,
etc., issued under its authority, and does not penalize employees for
actions committed in good faith and within the scope of their duties.
Twenty-two commenters state that since the FAA is responsible for
the transponder's design problems, either because of the FAA's short-
sighted approval of the TSO used to produce these transponders, or
because it decided to implement the Mode S ground sensors without
adequate research and testing to determine whether all transponders
would respond properly to the interrogations, the FAA should bear the
costs associated with modifying these transponders. The FAA does not
concur with the commenters. Although the FAA has determined that a
safety problem exists with the transponder's design, the manufacturer
is responsible for the design. The technical performance standards for
airborne air traffic control (ATC) transponder equipment (TSO-C74c)
were developed by a committee comprised of both government and industry
representatives. A representative of the transponder manufacturer is
included on the membership list for that committee. There have been no
reports of other manufacturers having a similar transponder design
deficiency. Additionally, the FAA's budget does not include allocations
to cover AD costs incurred in modifying privately-owned equipment.
Since the issuance of the NPRM, the manufacturer has issued
Revision 1 to Mandatory Service Bulletin (MSB) No. SB-104 on June 27,
1994. This revision adds an additional optional modification method to
the original MSB No. SB-104, dated March 14, 1994, that was proposed to
be incorporated by reference in the NPRM. Since the revised MSB imposes
no additional burden on operators and is an optional relieving
provision, MSB No. SB-104, Revision 1, dated June 27, 1994, is
incorporated by reference in this final rule. Additionally, since the
issuance of the NPRM, the FAA has reevaluated the labor rate, and based
upon this evaluation, has increased the hourly labor rate to $60 per
work hour instead of the proposed $55 per work hour. This change
increases the estimated overall cost of this AD by $37,500 to
$1,940,000.
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule with only editorial changes
and the changes described previously. The FAA has determined that these
changes will neither increase the economic burden on any operator nor
increase the scope of the AD.
The FAA estimates that 5,000 aircraft of U.S. registry will be
affected by this AD, that it will take approximately 1.5 work hours per
aircraft to accomplish the required actions, and that the average labor
rate is $60 per work hour. Required parts will cost approximately $298
per aircraft. Based on these figures, the total cost impact of the AD
on U.S. operators is estimated to be $1,940,000.
The regulations adopted herein will not have substantial direct
effects 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. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does not have sufficient federalism implications to warrant the
preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding a new airworthiness directive
to read as follows:
95-01-01 Terra Corporation: Amendment 39-9112. Docket No. 94-SW-03-
AD.
Applicability: Model TRT 250 transponders, part number (P/N)
0900-0250-00, with serial numbers (S/N) 4194 and below, Modification
Level (Mod Level) 4 and below; 3-inch ATI-mounted TRT 250 pushbutton
transponders, P/N 0900-0250-20, with S/N 5324 and below, Mod Level 4
and below; and TRT 250 D digital display transponders, P/N 0900-
0250-30, with S/N 1155 and below, Mod Level 1 and below.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the transponder to respond properly to
Mode S interrogations from Mode S ground stations and Traffic
Collision Avoidance System (TCAS) II airborne equipment, which could
result in loss of airspace separation, accomplish the following:
(a) Within 6 months after the effective date of this AD, remove
the TRT 250 series transponder in accordance with the procedures
stated in the Accomplishment Section of Terra Corporation Mandatory
Service Bulletin No. SB-104 (SB-104), Revision 1, dated June 27,
1994, and determine the part number (P/N), serial number (S/N), and
modification level (Mod Level).
(b) If the determination made in paragraph (a) reveals one of
the affected part numbers, serial numbers, and modification levels
indicated in this AD, replace the affected transponder with:
(1) A Terra Corporation transponder that has been modified in
accordance with the provisions of SB-104, Revision 1, dated June 27,
1994;
(2) An unaffected Terra Corporation transponder; or,
(3) Another manufacturer's transponder that responds properly to
Mode S interrogations from both an Air Traffic Control Radio Beacon
System (ATCRBS)/Mode S ground station and TCAS II airborne
equipment.
(c) If installing a replacement Terra Corporation transponder
that has been modified in accordance with the provisions of SB-104,
Revision 1, dated June 27, 1994, perform a ramp test in accordance
with the Testing section of SB-104, Revision 1, dated June 27, 1994.
Conduct the tests and checks required by section 91.413 of the
Federal Aviation Regulations (14 CFR 91.413) prior to approving the
aircraft for return to service.
(d) Installation of an affected Terra Corporation transponder
that has been modified and tested in accordance with SB-104,
Revision 1, dated June 27, 1994, or another transponder that
responds properly to Mode S interrogations from both an ATCRBS/Mode
S ground station and TCAS II airborne equipment constitutes
terminating action for the requirements of this AD.
(e) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used when approved by the Manager, Airplane Certification Office,
FAA, Rotorcraft Directorate. Operators shall submit their requests
through an FAA Principal Avionics Inspector, who may concur or
comment and then send it to the Manager, Airplane Certification
Office.
Note: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Airplane Certification Office.
(f) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the aircraft to a location where
the requirements of this AD can be accomplished.
(g) The modification shall be done in accordance with Terra
Corporation Mandatory Service Bulletin No. SB-104, Revision 1, dated
June 27, 1994. This incorporation by reference was approved by the
Director of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51. Copies may be obtained from Terra Corporation,
3520 Pan American Freeway NE, Albuquerque, New Mexico, 87107-4796.
Copies may be inspected at the FAA, Office of the Assistant Chief
Counsel, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the
Office of the Federal Register, 800 North Capitol Street, NW., suite
700, Washington, DC.
(h) This amendment becomes effective on February 6, 1995.
Issued in Fort Worth, Texas, on December 21, 1994.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 94-31903 Filed 12-28-94; 8:45 am]
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