Special Conditions: Honda Aircraft Company LLC Model HA-480 Airplane; High Altitude Operation
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...
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
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.
Docket:
Background documents or comments received may be read at
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:
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
kamruz.zaman@faa.gov.
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
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 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 § 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 § 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 § 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 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
( printed 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 § 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 § 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.
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 § 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.
www.regulations.gov
title 14, Code of Federal Regulations
5 U.S.C. 552