Document ID: FAA-2021-1035-0001
Agency: faa
Document Type: Rule
Title: Special Conditions: Airbus Model A321neo XLR Airplane; Side-Stick Controller—Controllability and Maneuverability
Posted Date: 2023-07-21T04:00Z

[Federal Register Volume 88, Number 139 (Friday, July 21, 2023)]
[Rules and Regulations]
[Pages 46956-46958]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-15466]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2021-1035; Special Conditions No. 25-819-SC]

Special Conditions: Airbus Model A321neo XLR Airplane; Side-Stick 
Controller--Controllability and Maneuverability

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Airbus Model 
A321neo XLR airplanes. The airplane 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 side-stick controllers for pitch and roll control. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. These 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.

[[Page 46957]]

DATES: This action is effective on Airbus on July 21, 2023. Send 
comments on or before September 5, 2023.

ADDRESSES: Send comments identified by Docket No. FAA-2021-1035 using 
any of the following methods:
     Federal eRegulations Portal: Go to https://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 title 14, Code of Federal Regulations (14 CFR) 11.35, the 
FAA will post all comments received without change to https://www.regulations.gov/, 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 Unit, AIR-621A, Technical 
Policy Branch, Policy and Standards Division, Aircraft Certification 
Service, Federal Aviation Administration, 1801 S Airport Rd., Wichita, 
KS 67209-2190; telephone and fax 405-666-1050; email 
[email protected]. 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 
https://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: Troy Brown, Performance and 
Environment Unit, AIR-621A, Technical Policy Branch, Policy and 
Standards Division, Aircraft Certification Service, Federal Aviation 
Administration, 1801 S Airport Rd., Wichita, KS 67209-2190; telephone 
and fax 405-666-1050; email [email protected].

SUPPLEMENTARY INFORMATION: The substance of these special conditions 
has been published in the Federal Register for public comment in 
several prior instances with no substantive comments received. 
Therefore, the FAA finds, pursuant to Sec.  11.38(b), that new comments 
are unlikely, and notice and comment prior to this publication are 
unnecessary.

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 -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: Side-stick controllers for 
pitch and roll control.

Discussion

    These proposed special conditions for the Airbus A321neo XLR 
airplane address the novel features of the side-stick controllers. The 
A321neo XLR will incorporate side-stick controllers controlling a fly-
by-wire (FBW) electronic flight control system (EFCS). This system 
provides an electronic interface between the pilot's flight controls 
and the flight control surfaces for both normal and failure states, and 
it generates the actual surface commands that provide for stability 
augmentation and control about all three airplane axes. In addition, 
pilot control authority may be uncertain, because the side-stick 
controllers are not mechanically interconnected as with conventional 
wheel and column controls.
    Current FAA regulations do not specifically address the use of 
side-stick controllers for pitch and roll control.

[[Page 46958]]

The unique features of the side stick must therefore be demonstrated 
through flight and simulator tests to have suitable handling and 
control characteristics when considering the following:
    1. The handling-qualities tasks and requirements of the Airbus 
Model A321neo XLR airplane special conditions, and other 14 CFR part 25 
requirements for stability, control, and maneuverability, including the 
effects of turbulence.
    2. General ergonomics: Armrest comfort and support, local freedom 
of movement, displacement angle suitability, and axis harmony.
    3. Inadvertent input in turbulence.
    4. Inadvertent pitch-roll crosstalk.
    The FAA Handling Qualities Rating Method (HQRM) of Appendix E of 
the Flight Test Guide for Certification of Transport Category 
Airplanes, AC 25-7D, may be, but is not required to be, used to show 
compliance.
    These 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 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 Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Airbus Model A321neo XLR airplanes.
    (a) Pilot Strength. In lieu of the ``strength of pilots'' limits of 
Sec.  25.143(d) for pitch and roll, and in lieu of the specific pitch 
force requirements of Sec. Sec.  25.145(b) and 25.175(d), the following 
applies:
    The applicant must show that the temporary and maximum prolonged 
force levels for the side-stick controllers are suitable for all 
expected operating conditions and configurations, whether normal or 
non-normal.
    (b) Controller Coupling. The electronic side-stick controller 
coupling design must provide for corrective and/or overriding control 
inputs by either pilot with no unsafe characteristics. Annunciation of 
controller status must be provided and must not be confusing to the 
flightcrew.
    (c) Pilot Control. The applicant must show by flight tests that the 
use of side-stick controllers does not produce unsuitable pilot-in-the-
loop control characteristics when considering precision path control 
tasks and turbulence. In addition, pitch and roll control-force 
sensitivity and displacement sensitivity must be compatible, so that 
normal inputs on one control axis will not cause significant 
unintentional inputs on the other.

    Issued in Kansas City, Missouri, on July 17, 2023.
Patrick R. Mullen,
Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2023-15466 Filed 7-20-23; 8:45 am]
BILLING CODE 4910-13-P