[Federal Register Volume 88, Number 111 (Friday, June 9, 2023)]
[Proposed Rules]
[Pages 37805-37807]
[FR Doc No: 2023-12310]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 21

[Docket No. FAA-2022-1726]

Airworthiness Criteria: Special Class Airworthiness Criteria for
the AgustaWestland Philadelphia Corporation Model AW609 Powered-Lift

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed airworthiness criteria.

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SUMMARY: The FAA announces the availability of, and requests comments
on, the proposed airworthiness criteria for the AgustaWestland
Philadelphia Corporation (AWPC) Model AW609 powered-lift. This document
proposes airworthiness criteria the FAA finds to be appropriate and
applicable for the powered-lift design.

DATES: The FAA must receive comments by July 10, 2023.

ADDRESSES: Send comments identified by Docket No. FAA-2022-1726 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 of 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<PHONE_NUMBER>.
    Privacy: The FAA will post all comments it receives, without
change, to https://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), as well as at https://DocketsInfo.dot.gov.
    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: Clinton Jones, Strategic Policy
Management Branch, AIR-613, Policy and Innovation Division, Aircraft
Certification Service, Federal Aviation Administration, 2200 S 216th
St, Des Moines, WA 98198; telephone and fax<PHONE_NUMBER>; email
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested people to take part in the development
of proposed airworthiness criteria for the AWPC Model AW609 powered-
lift by sending written comments, data, or views. Please identify the
AWPC Model AW609 and Docket No. FAA-2022-1726 on all submitted
correspondence. The most helpful comments reference a specific portion
of the airworthiness criteria, explain the reason for a recommended
change, and include supporting data.
    Except for Confidential Business Information 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 file in the
docket all comments received, as well as a report summarizing each
substantive public contact with FAA personnel concerning these proposed
airworthiness criteria. Before acting on this proposal, the FAA will
consider all comments received on or before the closing date for
comments. The FAA will consider comments filed late if it is possible
to do so without incurring delay. The FAA may change these
airworthiness criteria based on received comments.

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
this notice contain commercial or financial information that is
customarily treated as private, that you actually treat as private, and
that is relevant or responsive to this notice, 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 this notice. Submissions
containing CBI should be sent to the individual listed under FOR
FURTHER INFORMATION CONTACT. Any commentary that the FAA receives that
is not specifically designated as CBI will be placed in the public
docket for this notice.

Background

    The AWPC Model AW609 is a two-engine powered-lift with a maximum
weight of 17,500 lbs., and two crew and nine passenger seats. The
aircraft has two ``proprotors'' instead of propellers or rotors. The
AW609 design is a direct descendant of the Bell Helicopter Model BA609
certification project, which had design origins from the experimental
Bell XV-15 aircraft.
    After several changes of applicants, on February 15, 2012,
AgustaWestland Tilt-Rotor Company, now AWPC, applied for a type
certificate for the Model AW609. Under 14 CFR 21.17(c), an application
for type certification is effective for three years, unless the FAA
approves a longer period. Section 21.17(d) provides that, where a type
certificate has not been issued within the time limit established under
section 21.17(c), the applicant may file for an extension and update
the designated applicable regulations in the type certification basis.
Since the project was not certificated within the established time
limit, the FAA approved a series of requests for extension by AWPC. As
a result, the date of the updated type certification basis is March 31,
2021.

Discussion

    Powered-lift are type certificated as special class aircraft
because the FAA has not yet established powered-lift airworthiness
standards as a separate part of subchapter C of 14 CFR. Under the
procedures in 14 CFR 21.17(b), the airworthiness requirements for
special class aircraft are the portions of the requirements in parts
23, 25, 27, 29, 31, 33, and 35 found by the FAA to be appropriate and
applicable to the specific type design and any other airworthiness
criteria found by the FAA to provide an equivalent level of safety to
the existing standards. This notice announces the applicable
regulations and other airworthiness criteria developed for type
certification of the Model AW609 powered-lift under Sec.  21.17(b).
    The powered-lift has characteristics of both a rotorcraft and an
airplane. It is designed to function as a helicopter for takeoff and
landing and as an airplane cruising at higher speeds than a helicopter
during the enroute portion of flight operations. Accordingly, the
proposed Model AW609 certification basis contains standards from parts
23, 25, and 29, as well as other airworthiness criteria specific for a
powered-lift.
    This certification basis includes part 23, part 25, and part 29
airworthiness standards. These are part 23 at amendment 23-62, part 25
at amendment 25-135 (except Sec.  25.903(a) at amendment 25-140), and
part 29 at amendment 29-55. The proposed certification basis
incorporates by reference existing transport category airplane and
rotorcraft standards, one normal category airplane standard, Category A
rotorcraft standards, optional Category B rotorcraft standards, and
criteria for operation under instrument flight rules. This
certification basis is not established for flight into known icing
conditions.
    The proposed certification basis also includes new criteria unique
to the powered-lift design, designated as Tiltrotor (TR) criteria. Many
of these TR criteria consist of modified part 25 or part 29 standards.
Some include criteria that combine existing parts 23, 25, and 29
standards, as the maximum weight of the Model AW609 exceeds the weight
for normal category rotorcraft and most part 23 category airplanes, but
its passenger seating is less than that of a transport category
airplane or a transport category rotorcraft. The FAA also developed TR
criteria because no existing standard captures the powered-lift's
transitional flight modes (during flight, the powered-lift nacelle
rotates the proprotor system from providing vertical lift to horizontal
propulsion). The TR criteria also contain definitions specific for the
powered-lift, such as flight modes, configurations, speeds, and
terminology (``flaperon'' instead of ``aileron'' or ``flap;''
``proprotor'' instead of ``rotor'' or ``propeller'').
    For example, while existing part 25 and part 29 standards for
passenger emergency exits include a size classification (types I, II,
III, IV) depending on the passenger seating capacity and other factors,
the proposed certification basis has a TR with criteria for the
specific type of passenger emergency exit that is part of the design of
the Model AW609. Another example involves fatigue evaluation. Part 25
contains requirements such as a limit of validity (LOV) on airframe
fatigue for pressurized fuselages, which are not in part 29. Instead,
fatigue evaluation in part 29 includes a composite structures fatigue
rule, due to the more extreme fatigue environment of rotorcraft. For
small airplanes, part 23, amendment 23-48, added a composite airframe
evaluation requirement for bonded joints, which is included in agency
compliance guidance for parts 25 and 29 but not required by a specific
regulation (the safety requirement is complied with through other broad
existing regulations in those parts). Since the Model AW609 has a
pressurized fuselage, the FAA developed TR criteria to include the LOV
requirement. The proposed certification basis incorporates by reference
the part 29 composite rotorcraft structures fatigue rule, TR criteria
to include the composite bonding requirements from part 23, as well as
TR criteria to include fatigue requirements for elastomeric primary
structural elements.

Applicability

    These airworthiness criteria, established under the provisions of
Sec.  21.17(b), are applicable to the AWPC Model AW609 powered-lift.
Should AWPC wish to apply these airworthiness criteria to other
powered-lift models, it must submit a new application for a type
certificate.

Proposed Airworthiness Criteria

    The FAA proposes airworthiness criteria for type certification of
the AgustaWestland Philadelphia Corporation Model AW609 powered-lift.
You may view the airworthiness criteria on the internet at https://www.regulations.gov in Docket No. FAA-2022-1726. You may also obtain a
copy of the airworthiness criteria by contacting the individual listed
in the FOR FURTHER INFORMATION CONTACT section of this notice.

    Issued in Washington, DC, on May 19, 2023.
Ian Lucas,
Manager, Certification Coordination Section, Policy and Standards
Division, Aircraft Certification Service.
[FR Doc. 2023-12310 Filed 6-8-23; 8:45 am]
BILLING CODE 4910-13-P