[Federal Register Volume 88, Number 111 (Friday, June 9, 2023)]
[Proposed Rules]
[Pages 37805-37807]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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 202-493-2251.
    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 206-231-3181; 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.

[[Page 37806]]

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.


[[Page 37807]]


    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


