# [Amended]
**AGENCY:**
Federal Aviation Administration (FAA), DOT.
**ACTION:**
Notice of proposed rulemaking (NPRM).
**SUMMARY:**
The FAA proposes to adopt a new airworthiness directive (AD) for certain Honda Aircraft Company LLC (Honda) Model HA-420 airplanes. This proposed AD was prompted by the discovery of a gap between the trailing edge wing nut plates and leading edge aileron balance weights being less than the minimum required clearance. This proposed AD would require replacing the affected left and right aileron fixed balance weights with reduced geometry fixed balance weights. The FAA is proposing this AD to address the unsafe condition on these products.
**DATES:**
The FAA must receive comments on this proposed AD by August 21, 2025.
**ADDRESSES:**
You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:
• *Federal eRulemaking Portal:* Go to *regulations.gov* . Follow the instructions for submitting comments.
• *Fax:* (202) 493-2251.
• *Mail:* U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
• *Hand Delivery:* Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.
*AD Docket:* You may examine the AD docket at *regulations.gov* under Docket No. FAA-2025-1355; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this NPRM, any comments received, and other information. The street address for Docket Operations is listed above.
*Material Incorporated by Reference:*
• For Honda Aircraft Company material identified in this proposed AD, contact Honda, 6430 Ballinger Road, Greensboro, NC 27410; phone: (336) 662-0246; website: *hondajet.com* .
• You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110.
**FOR FURTHER INFORMATION CONTACT:**
Tuan Tran, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5522; email: *[email protected].*
**SUPPLEMENTARY INFORMATION:**
**Comments Invited**
The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the *ADDRESSES* section. Include “Docket No. FAA-2025-1355; Project Identifier AD-2025-00016-A” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may revise this proposal because of those comments.
Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to *regulations.gov,* including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM.
**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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to Tuan Tran, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
**Background**
The FAA was advised that, during a production quality assurance inspection, a gap between the trailing edge wing nut plates and leading edge aileron balance weights was discovered with less than the minimum required clearance on a Honda Model HA-420 airplane. Starting with airplane serial number 235, the wing trailing edge nut plates were relocated closer to the trailing edge to standardize the manufacturing process and improve interchangeability among different serial-numbered airplanes. Relocating these nut plates reduced the gap between the nut plates and the balance weights. This reduction could result in jamming or contact between the balance weights and the nut plates, negatively affecting flight and causing damage to the airplane. The unsafe condition, if not addressed, could result in loss of control of the airplane.
**FAA's Determination**
The FAA is issuing this NPRM after determining that the unsafe condition described previously is likely to exist or develop on other products of the same type design.
**Material Incorporated by Reference Under 1 CFR Part 51**
The FAA reviewed Honda Aircraft Company Service Bulletin No. SB-420-27-011, Revision B, dated December 24, 2024. This material specifies procedures for replacing the affected left and right aileron fixed balance weights with reduced geometry fixed balance weights to ensure the minimum required clearances are maintained with the adjacent wing trailing edge panel fasteners.
This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the *ADDRESSES* section.
**Proposed AD Requirements in This NPRM**
This proposed AD would require accomplishing the actions specified in the service information already described, except as discussed under “Differences Between this Proposed AD and the Referenced Material.”
**Differences Between This Proposed AD and the Referenced Material**
Honda SB No. SB-4-20-27-011, Revision B, specifies contacting Honda if proper aileron balance cannot be attained using adjustable balance weights, but this proposed AD would require using a procedure approved by the Manager, East Certification Branch, FAA.
**Costs of Compliance**
The FAA estimates that this AD, if adopted as proposed, would affect 38 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
| Action | Labor cost | Parts cost | Cost per | Cost on U.S. |
| --- | --- | --- | --- | --- |
| Replace the left and right inboard and outboard fixed balance weights | 45 work-hours × $85 per hour = $3,825 | $3,676 | $7,501 | $285,038 |
The instructions for repair could vary significantly from airplane to airplane if proper aileron balance cannot be attained using adjustable balance weights. The FAA has no way of determining the cost of this repair or the number of airplanes that may require repair.
The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected operators.
**Authority for This Rulemaking**
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: General requirements. Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
**Regulatory Findings**
The FAA determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify this proposed regulation:
(1) Is not a “significant regulatory action” under Executive Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
**List of Subjects in 14 CFR Part 39**
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
**The Proposed Amendment**
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
**PART 39—AIRWORTHINESS DIRECTIVES**
1. The authority citation for part 39 continues to read as follows:
**Authority:**
49 U.S.C. 106(g), 40113, 44701.
§ 39.13
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
*Honda Aircraft Company LLC:* Docket No. FAA-2025-1355; Project Identifier AD-2025-00016-A.
**(a) Comments Due Date**
The FAA must receive comments on this airworthiness directive (AD) by August 21, 2025.
**(b) Affected ADs**
None.
**(c) Applicability**
This AD applies to Honda Aircraft Company LLC (Honda) Model HA-420 airplanes, serial numbers 42000172, 42000235 through 42000265 inclusive, and 42000267 through 42000272 inclusive, certificated in any category, with aileron balance weight part number HJ1-15751-152-003 or HJ1-15751-157-003 installed.
**(d) Subject**
Joint Aircraft System Component (JASC) Code 2710, Aileron Control System.
**(e) Unsafe Condition**
This AD was prompted by the discovery that the gap between the trailing edge wing nut plates and leading edge aileron balance weights may be less than the minimum required clearance. The FAA is issuing this AD to prevent jamming or contact between the balance weights and the nut plates. The unsafe condition, if not addressed, could result in loss of control of the airplane.
**(f) Compliance**
Comply with this AD within the compliance times specified, unless already done.
**(g) Required Actions**
Before further flight after the effective date of this AD, replace the left and right aileron fixed balance weights in accordance with steps 3.0(3) through 3.0(8) of the Accomplishment Instructions in Honda Aircraft Company Service Bulletin No. SB-420-27-011, Revision B, dated December 24, 2024 (Honda SB No. SB-4-20-27-011, Revision B), except as provided in paragraphs (g)(1) through (3) of this AD.
(1) Instead of discarding parts, you must remove those parts from service.
(2) This AD does not require returning parts to the manufacturer.
(3) Instead of contacting Honda if proper aileron balance cannot be attained using adjustable balance weights, this AD requires attaining proper aileron balance using a procedure approved by the Manager, East Certification Branch, FAA.
**(h) Alternative Methods of Compliance (AMOCs)**
(1) The Manager, East Certification Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the East Certification Branch, send it to the attention of the person identified in paragraph (i) of this AD and email to: *[email protected]* .
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
(3) For material that contains steps that are labeled as RC the provisions of paragraphs (h)(3)(i) and (ii) of this AD apply.
(i) The steps labeled as RC, including substeps under an RC step and any figures identified in an RC step, must be done to comply with the AD. An AMOC is required for any deviations to RC steps, including substeps and identified figures.
(ii) Steps not labeled as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC, provided the RC steps, including substeps and identified figures, can still be done as specified, and the airplane can be put back in an airworthy condition.
**(i) Additional Information**
For more information about this AD, contact Tuan Tran, Aviation Safety Engineer, FAA, 1701 Columbia Avenue, College Park, GA 30337; phone: (404) 474-5522; email: *[email protected].*
**(j) Material Incorporated by Reference**
(1) The Director of the Federal Register approved the incorporation by reference (IBR) of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
(2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise.
(i) Honda Aircraft Company Service Bulletin No. SB-420-27-011, Revision B, dated December 24, 2024.
(ii) [Reserved]
(3) For Honda Aircraft Company material identified in this AD, contact Honda, 6430 Ballinger Road, Greensboro NC 27410; phone: (336) 662-0246; website: *hondajet.com* .
(4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (817) 222-5110.
(5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit *www.archives.gov/federal-register/cfr/ibr-locations* or email *[email protected]* .
Issued on July 1, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.