[Federal Register Volume 86, Number 18 (Friday, January 29, 2021)]
[Proposed Rules]
[Pages 7516-7518]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-01958]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 29
[Docket No. FAA-2021-0065; Notice No. 29-054-SC]
Special Conditions: Bell Textron Inc., Model 525 Helicopter; Fly-
By-Wire (FBW) Flight Control System (FCS)
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the Bell Textron
Inc. (Bell) Model 525 helicopter. This helicopter will have a novel or
unusual design feature associated with a fly-by-wire (FBW) flight
control system (FCS). The applicable airworthiness regulations do not
contain adequate or appropriate safety standards for this design
feature. These proposed special conditions contain the additional
safety standards that the Administrator considers necessary to
establish a level of safety equivalent to that established by the
existing airworthiness standards.
DATES: Send comments on or before March 15, 2021.
ADDRESSES: Send comments identified by Docket No. FAA-2021-0065 using
any of the following methods:
Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending
your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: Except for Confidential Business Information (CBI) as
described in the following paragraph, and other information as
described in 14 CFR 11.35, the FAA will post all comments it receives,
without change, to http://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket website, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478).
Confidential Business Information: CBI is commercial or financial
information that is both customarily and actually treated as private by
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552),
CBI is exempt from public disclosure. If your comments responsive to
these proposed special conditions contain commercial or financial
information that is customarily treated as private, that you actually
treat as private, and that is relevant or responsive to these proposed
special conditions, it is important that you clearly designate the
submitted comments as CBI. Please mark each page of your submission
containing CBI as ``PROPIN.'' The FAA will treat such marked
submissions as confidential under the FOIA, and they will not be placed
in the public docket of these proposed special conditions. Submissions
containing CBI should be sent to John VanHoudt, FAA, Dynamic Systems
Section, AIR-627, Technical Innovation Policy Branch, Policy and
Innovation Division, Aircraft Certification Service, 10101 Hillwood
Parkway, Fort Worth, TX 76177-98198; telephone and fax 817-222-5193;
email [email protected]. Any commentary that the FAA receives
which is not specifically designated as CBI will be placed in the
public docket for this rulemaking.
Docket: Background documents or comments received may be read at
http://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to Docket Operations in Room W12-140 of
the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: John VanHoudt, FAA, Dynamic Systems
Section, AIR-627, Technical Innovation Policy Branch, Policy and
Innovation Division, Aircraft Certification Service, 10101 Hillwood
Parkway, Fort Worth, TX 76177-98198; telephone and fax 817-222-5193;
email [email protected].
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2021-0065; Notice No. 29-054-
SC'' at the beginning of your comments. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
these proposed special conditions because of those comments.
Background
On December 15, 2011, Bell applied for a type certificate for a new
14 CFR part 29 transport category helicopter designated as the Model
525. Bell applied for multiple extensions, with the most recent
occurring on November 12, 2020. The date of the updated type
certification basis is December 31, 2016, based upon the applicant's
proposed type certificate issuance date of December 31, 2021. The Model
525 is a medium twin-engine rotorcraft. The design maximum takeoff
weight is 20,500 pounds, with a maximum capacity of 19 passengers and a
crew of 2.
The Bell Model 525 helicopter will be equipped with a four axis
full authority digital FBW FCS that provides for aircraft control
through pilot input and coupled flight director modes. The design of
the Bell Model 525 FBW controls, which provides no direct hydro-
mechanical linkage between the primary cockpit flight controls or
inceptors and the main and tail rotor
[[Page 7517]]
actuators, is a first for commercial rotorcraft use. Therefore, the
regulations do not contain adequate or appropriate safety standards for
this new design feature.
The rotorcraft industry is producing new generations of
helicopters, and gradually increasing size, speed, load capacity, and
technical sophistication. In recent years, an accelerated trend has
occurred using rotorcraft for a wide range of commercial and industrial
applications. This has resulted in increased complexity of modern
control systems and increased use of automation in flight control
systems, including the implementation of advanced flight control
systems such as FBW FCS.
Title 14, Code of Federal Regulations (CFR), Sec. 29.671(c), which
provides requirements for transport category rotorcraft control
systems, does not contain adequate or appropriate safety standards for
this new design feature. 14 CFR 29.671(c) requires, in part, a means to
allow the pilot to determine that full control authority is available
prior to flight. This command control authority is typically achieved
by verifying movement of the control quadrant through an unassisted
mechanical pilot-initiated manipulation of the primary flight controls
prior to flight. Although this approach does not guarantee that 100%
maximum control movement of the flight controls has been achieved prior
to flight, it has been deemed appropriate for mechanical flight control
systems.
Unlike traditional mechanical flight control systems, the FBW FCS
reduces the opportunity for jamming of the flight controls due to
mechanical bind, improper servo adjustment resulting from faulty
maintenance, or presence of a foreign object in the control mechanism
that will impair safety. This reduced exposure for jams is due to the
replacement of the mechanical linkages between the primary cockpit
flight controls or inceptors and the main and tail rotor actuators with
digital signal processing wiring. However, the FBW FCS does increase
the potential for latent failures or faults that could impair full
control authority, unless a means exists to ensure the FBW FCS is fully
functional and free of control authority impairment prior to flight. A
FBW system may have the ability to verify full control authority
without having to move the primary flight controls.
Although part 29 does not contain adequate or appropriate safety
standards for this novel or unusual design feature, 14 CFR 25.671,
amendment 25-23, provides these requirements for transport category
airplanes. Accordingly, these proposed special conditions are based on
Sec. 25.671 to provide requirements for a FBW FCS on the Bell Model
525 helicopter. 14 CFR 25.671(c) provides the same level of safety as
that intended by Sec. 29.671(c) when employing a FBW FCS by including
requirements for jamming and failure analysis. The proposed special
conditions would require a comprehensive safety analysis of the
aircraft's FBW FCS to include failures due to command logic (software),
mechanical and electronic interfaces to other systems, jamming and
maintenance. Therefore, in conjunction with Sec. 29.671(a) and (b),
the proposed special conditions incorporate provisions from Sec.
25.671(c) to establish a level of safety equivalent to that established
in the regulations.
Type Certification Basis
Under the provisions of 14 CFR 21.17, Bell must show that the Model
525 helicopter meets the applicable provisions of part 29, as amended
by Amendments 29 through 55 thereto. The Bell Model 525 certification
basis date is December 31, 2016.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 29) do not contain adequate or
appropriate safety standards for the Bell Model 525 because of a novel
or unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the special conditions would also
apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Bell Model 525 helicopter must comply with the the
noise certification requirements of 14 CFR part 36, and the FAA must
issue a finding of regulatory adequacy under Sec. 611 of Public Law
92-574, the ``Noise Control Act of 1972.''.
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type-
certification basis under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The Bell Model 525 helicopter will incorporate the following novel
or unusual design features: A FBW FCS.
This new design feature has no direct hydro-mechanical linkage
between the primary cockpit flight controls or inceptors and the main
and tail rotor actuators, thereby eliminating the more complex elements
of either a manual movement of the controls by the pilot, or another
manual means.
Discussion
The proposed special conditions would require that a means be
available to show full control authority for all powered control
systems.
The proposed special conditions contain the additional safety
standards that the Administrator considers necessary to establish a
level of safety equivalent to that established by the existing
airworthiness standards.
Applicability
As discussed above, these special conditions are applicable to the
Bell Model 525 helicopter. Should Bell apply at a later date for a
change to the type certificate to include aother model incorporating
the same novel or unusual design feature, these special conditions
would apply to that model as well.
Conclusion
This action affects only a certain novel or unusual design feature
on the Bell Model 525 helicopter. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 29
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
Authority Citation
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions in lieu of Sec. 29.671(c) as part of the
type certification basis for the Bell Textron Inc. Model 525
helicopter:
The rotorcraft must be shown by analysis, tests, or both, to be
capable of continued safe flight and landing after any of the following
failures or jamming in the flight control system within the normal
flight envelope, without requiring exceptional piloting skill or
strength. Probable failures must have only minor effects.
(1) Any single failure not shown to be extremely improbable,
excluding jamming.
(2) Any combination of failures not shown to be extremely
improbable, excluding jamming.
(3) Any jam in a control position normally encountered during
hover, takeoff, climb, cruise, normal turns,
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descent, and landing, unless the jam is shown to be extremely
improbable or can be alleviated.
Issued in Fort Worth, Texas.
Jorge Castillo,
Manager, Strategic Policy Rotorcraft Section, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2021-01958 Filed 1-28-21; 8:45 am]
BILLING CODE 4910-13-P