Special Conditions: Honda Aircraft Company LLC Model HA-480 Airplane; High Altitude Operation

Issuing agencies

Abstract

This action proposes special conditions for the Honda Aircraft Company LLC (Honda) Model HA-480 airplane. This airplane will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for normal category airplanes. This airplane will have design features associated with high altitude operations up to 47,000 feet. 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 91 Issue 191 (Monday, October 5, 2026)</title>
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[Federal Register Volume 91, Number 191 (Monday, October 5, 2026)]
[Proposed Rules]
[Pages 63170-63172]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-20350]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. FAA-2025-5730; Notice No. 23-26-01-SC]


Special Conditions: Honda Aircraft Company LLC Model HA-480 
Airplane; High Altitude Operation

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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[[Page 63171]]

SUMMARY: This action proposes special conditions for the Honda Aircraft 
Company LLC (Honda) Model HA-480 airplane. This airplane will have a 
novel or unusual design feature when compared to the state of 
technology envisioned in the airworthiness standards for normal 
category airplanes. This airplane will have design features associated 
with high altitude operations up to 47,000 feet. 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 November 19, 2026.

ADDRESSES: Send comments identified by Docket No. FAA-2025-5730 using 
any of the following methods:
    Federal eRegulations Portal: Go to <a href="http://www.regulations.gov">www.regulations.gov</a> 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.
    Docket: Background documents or comments received may be read at 
<a href="http://www.regulations.gov">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: Kamruz Zaman, Airframe, AIR-622, 
Technical Policy Branch, Aircraft Certification Service, Federal 
Aviation Administration, 1600 Stewart Avenue, Suite 410, Westbury, NY 
11590; telephone (516) 228-7355; email <a href="/cdn-cgi/l/email-protection#e98288849b9c93c79388848887a98f8888c78e869f"><span class="__cf_email__" data-cfemail="c3a8a2aeb1b6b9edb9a2aea2ad83a5a2a2eda4acb5">[email&#160;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 proposed 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, and will consider comments filed late if it is possible to do 
so without incurring delay. The FAA may change these special conditions 
based on the comments received.

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="http://www.regulations.gov">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 proposed special conditions. Send 
submissions containing CBI to the individual listed in the For Further 
Information Contact section above. Comments the FAA receives, which are 
not specifically designated as CBI, will be placed in the public docket 
for these proposed special conditions.

Background

    On February 21, 2019, Honda applied for an amendment to Type 
Certificate No. A00018AT to include the new Model HA-480 airplane. The 
Honda Model HA-480 airplane, which is a derivative of the Model HA-420 
currently approved under Type Certificate No. A00018AT, is a twin-
engine, normal category, commuter airplane with a maximum seating for 
11 passengers, and a maximum takeoff weight of 17,550 pounds.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Honda must show that the 
Model HA-480 airplane meets the applicable provisions of the 
regulations listed in Type Certificate No. A00018AT, 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 23) do not contain adequate or 
appropriate safety standards for the Honda Model HA-480 airplane 
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 Honda Model HA-480 airplane 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 Honda Model HA-480 airplane will incorporate the following 
novel or unusual design feature:
    This aircraft will operate at an altitude up to 47,000 feet.

Discussion

    The FAA considers certification of normal category airplanes for 
operations at altitudes greater than 41,000 feet to be a novel or 
unusual feature because current part 23 does not contain adequate 
standards to ensure the same level of safety as provided during 
operations at lower altitudes. Operation at 47,000 feet raises two 
concerns related to structures: (1) Pressure vessel integrity due to 
the higher differential

[[Page 63172]]

pressures and (2) The potential for depressurization that degrades the 
amount of breathable air for passengers and crew.
    These special conditions are being proposed to address pressure 
vessel integrity due to the higher differential pressures when 
operating at 47,000 feet. To ensure adequate pressure vessel strength, 
the FAA proposes a factor of 1.67 be applied to the maximum relief 
valve pressure level prescribed in Sec.  23.2225(c)(3), rather than the 
1.33 factor currently prescribed in that regulation.
    The FAA has previously issued Special Conditions No. 23-ACE-87, 
Docket No. FAA-2016-3462 (62 FR 58875, October 31, 1997), to another 
normal category turbojet airplane model for operation at high 
altitudes, to address the second concern noted above--breathable air 
and occupant safety. In those special conditions, damage tolerance 
methods were proposed to be used to assure pressure vessel integrity 
while operating at higher altitudes. This regulatory approach was also 
reflected in SC No. 23-102-SC, Docket No. 154 (65 FR 7283, February 14, 
2000) and the previously cited SC No. 23-ACE-87. Similar special 
conditions are not needed on the Honda HA-480 because part 23 
requirements have since been upgraded to include specific criteria for 
depressurization at altitudes above 45,000 feet. See 14 CFR 23.841(d) 
at Amendment 23-62. Honda has agreed to include these criteria as their 
means of compliance to Sec.  23.2320, Occupant physical environment.
    The proposed special conditions contain the additional safety 
standards that the Administrator considers necessary to establish a 
level of safety equivalent to those established by the existing 
airworthiness standards.

Applicability

    As discussed above, these proposed special conditions are 
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 apply to the other model as well.

Conclusion

    This action affects only a certain novel or unusual design feature 
on one model airplane. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 23

    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), 40113, 44701, 44702, and 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Honda Aircraft Company LLC Model HA-480 airplanes.

Pressure Vessel Integrity

    With regard to the fuselage structure design for cabin pressure 
capability above 45,000 feet, the pressure vessel structure, including 
doors and windows, must comply with Sec.  23.2225(c)(3), using a factor 
of 1.67 instead of the 1.33 factor prescribed.

    Issued in Des Moines, Washington, on October 1, 2026.
Paul R. Siegmund,
Branch Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2026-20350 Filed 10-2-26; 8:45 am]
BILLING CODE 4910-13-P


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