Proposed Rule2022-24772
Special Conditions: Airbus Model A321neo XLR Airplane; Flight-Envelope Protection Functions-General
Primary source
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Published
November 17, 2022
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
This action proposes special conditions for the the Airbus Model A321neo XLR airplanes. These airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport-category airplanes. This design feature is an electronic flight-control system that provides flight-envelope protections. 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.
Full Text
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<title>Federal Register, Volume 87 Issue 221 (Thursday, November 17, 2022)</title>
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[Federal Register Volume 87, Number 221 (Thursday, November 17, 2022)]
[Proposed Rules]
[Pages 68942-68944]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-24772]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2022-0349; Notice No. 25-22-05-SC]
Special Conditions: Airbus Model A321neo XLR Airplane; Flight-
Envelope Protection Functions--General
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the the Airbus
Model A321neo XLR airplanes. These airplanes will have a novel or
unusual design feature when compared to the state of technology
envisioned in the airworthiness standards for transport-category
airplanes. This design feature is an electronic flight-control system
that provides flight-envelope protections. The applicable airworthiness
regulations do not contain
[[Page 68943]]
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 January 3, 2023.
ADDRESSES: Send comments identified by Docket No. FAA-2022-0349 using
any of the following methods:
<bullet> Federal eRegulations Portal: Go to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> and follow the online instructions for sending
your comments electronically.
<bullet> 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.
<bullet> 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.
<bullet> 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 title 14, Code of Federal Regulations (14 CFR) 11.35, the
FAA will post all comments received without change to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, including any personal information you provide.
The FAA will also post a report summarizing each substantive verbal
contact received about these special conditions.
Confidential Business Information: 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 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 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 the indicated comments will not be placed in the public
docket of these special conditions. Send submissions containing CBI to
Troy Brown, Performance and Environment Section, AIR-625, Technical
Innovation Policy Branch, Policy and Innovation Division, Aircraft
Certification Service, Federal Aviation Administration, 1801 S. Airport
Rd., Wichita, KS 67209-2190; telephone and fax 405-666-1050; email
<a href="/cdn-cgi/l/email-protection#cbbfb9a4b2e5aae5a9b9a4bca58badaaaae5aca4bd"><span class="__cf_email__" data-cfemail="4b3f392432652a652939243c250b2d2a2a652c243d">[email protected]</span></a>. Comments the FAA receives, which are not
specifically designated as CBI, will be placed in the public docket for
these special conditions.
Docket: Background documents or comments received may be read at
<a href="https://www.regulations.gov/">https://www.regulations.gov/</a> 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: Troy Brown, Performance and
Environment Section, AIR-625, Technical Innovation Policy Branch,
Policy and Innovation Division, Aircraft Certification Service, Federal
Aviation Administration, 1801 S. Airport Rd., Wichita, KS 67209-2190;
telephone and fax 405-666-1050; email <a href="/cdn-cgi/l/email-protection#83f7f1ecfaade2ade1f1ecf4edc3e5e2e2ade4ecf5"><span class="__cf_email__" data-cfemail="7f0b0d1006511e511d0d1008113f191e1e51181009">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
Comments Invited
The FAA invites interested people to take part in this rulemaking
by sending written comments, data, or views. 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 for
comments. The FAA may change these special conditions based on the
comments received.
Background
On September 16, 2019, Airbus applied for an amendment to Type
Certificate No. A28NM to include the new Model A321neo XLR airplanes,
which include the Model A321-271NY and A321-253NY airplanes. These
airplanes are twin-engine, transport-category airplanes with seating
for 244 passengers and a maximum takeoff weight of 222,000 pounds.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Airbus must show that the
Model A321neo XLR airplanes meet the applicable provisions of the
regulations listed in Type Certificate No. A28NM, or the applicable
regulations in effect on the date of application for the change, except
for earlier amendments as agreed upon by the FAA.
If the Administrator finds that the applicable airworthiness
regulations (e.g., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Airbus Model A321neo XLR airplanes
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 novel or
unusual design feature, or should any other model already included on
the same type certificate be modified to incorporate the same novel or
unusual design feature, these special conditions would also apply to
the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Airbus Model A321neo XLR airplanes must comply with the
fuel-vent and exhaust-emission requirements of 14 CFR part 34, and the
noise-certification requirements of 14 CFR part 36.
The FAA issues special conditions, as defined in Sec. 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.101.
Novel or Unusual Design Features
The Airbus Model A321neo XLR airplanes will incorporate the
following novel or unusual design feature:
An electronic flight-control system that provides flight envelope
protections.
Discussion
Many new transport-category airplanes use advanced electronic
flight-control systems (EFCS), which incorporate flight-envelope
protection (limiting) designed to prevent the pilot from inadvertently
or intentionally exceeding any number of flight-envelope parameters.
Depending on a particular EFCS design, these limiting features may or
may not be active in all normal and alternate flight-control modes, and
may or may not be capable of being overridden by the pilot.
The FAA currently applies 14 CFR 25.143 to airplanes incorporating
EFCS. The purpose of Sec. 25.143 is to verify that operational
maneuvers conducted within the operational envelope can be accomplished
smoothly with average piloting skill, and without encountering a stall
warning or other characteristics that might interfere with normal
maneuvering, or without exceeding
[[Page 68944]]
structural limits. The airplane response to control input should be
predictable to the pilot. However, Sec. 25.143 does not adequately
ensure that airplanes incorporating EFCS with flight-envelope
protections will have a level of safety equivalent to that of existing
standards.
Envelope-protection functions are intended to reduce the likelihood
of excursions, either commanded or uncommanded, to unintended or
potentially hazardous airplane operating states. As a consequence of
preventing excursions, these functions can also restrict aircraft
maneuverability, and may introduce non-traditional behavior. The
proposed special conditions will ensure that flight-envelope protection
functions support safe operation, and do not interfere with required
maneuvering in normal and emergency operations, and in forseeable
atmospheric conditions.
The FAA previously issued separate special conditions for general
limiting, normal load-factor limiting, high-speed limiting, and pitch
and roll limiting for airplanes incorporating flight-envelope
protection features. However, the FAA tasked the Aviation Rulemaking
Advisory Committee (ARAC) in April 2014 (79 FR 20295) to develop
recommended standards for fly-by-wire flight controls for general
flight-envelope protection (limiting) similar to those provided for
conventional control functions in 14 CFR 25.143. The ARAC
recommended,\1\ among other things, performance-based requirements that
would encompass general limiting, normal load-factor limiting, high-
speed limiting, and pitch and roll limiting which the FAA previously
issued as separate special conditions. These proposed special
conditions are based on that ARAC recommendation.
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\1\ FAA Aviation Rulemaking Advisory Committee, FTHWG Topic 1
Envelope Protection, Recommendation Report-Rev. A, March, 2017,
<a href="https://www.faa.gov/regulations_policies/rulemaking/committees/documents/media/09%20-%20FTHWG_Final_Report_Phase_2_RevA__Apr_2017.pdf">https://www.faa.gov/regulations_policies/rulemaking/committees/documents/media/09%20-%20FTHWG_Final_Report_Phase_2_RevA__Apr_2017.pdf</a>.
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These proposed special conditions provide the same level of safety
as the prescriptive, design-specific special conditions the FAA has
issued in the past for general limiting, normal load-factor limiting,
high-speed limiting, and pitch and roll limiting, thus the FAA need not
issue separate special conditions to address each of these areas.
These proposed special conditions are in addition to the
requirements of Sec. 25.143. 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.
Applicability
As discussed above, these proposed special conditions apply to
Airbus Model A321neo XLR airplanes. Should Airbus apply later for a
change to the type certificate to include another model incorporating
the same novel or unusual design feature, the special conditions would
apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model series of airplanes. It is not a rule of general
applicability.
List of Subjects in 14 CFR Part 25
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 as part of the type certification basis
for Airbus Model A321neo XLR airplanes equipped with EFCS.
In addition to Sec. 25.143, the following requirements apply:
(a) Envelope protection functions must not unduly limit the
maneuvering capability of the airplane, nor interfere with its ability
to perform maneuvers required for normal and emergency operations.
(b) Onset characteristics of each flight-envelope protection
function must be appropriate to the phase of flight and type of
maneuver, and must not conflict with the ability of the pilot to
satisfactorily control the airplane flight path, speed, and attitude.
(c) Excursions of a limited flight parameter beyond its nominal
design-limit value due to dynamic maneuvering, airframe and system
tolerances, and non-steady atmospheric conditions must not result in
unsafe flight characteristics or conditions.
(d) Operation of flight-envelope protection functions must not
adversely affect aircraft control during expected levels of atmospheric
disturbances, nor impede the application of recovery procedures in case
of wind shear.
(e) Simultaneous action of flight-envelope protection functions
must not result in adverse coupling or adverse priority.
(f) In case of abnormal attitude or excursion of flight parameters
outside the protected boundaries, operation of flight-envelope
protection functions must not hinder airplane recovery.
Issued in Kansas City, Missouri, on November 8, 2022.
Patrick R. Mullen,
Manager, Technical Innovation Policy Branch, Policy and Innovation
Division, Aircraft Certification Service.
[FR Doc. 2022-24772 Filed 11-16-22; 8:45 am]
BILLING CODE 4910-13-P
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