This site displays a prototype of a “Web 2.0” version of the daily Federal Register. It is not an official legal edition of the Federal Register, and does not replace the official print version or the official electronic version on GPO’s govinfo.gov.
The documents posted on this site are XML renditions of published Federal Register documents. Each document posted on the site includes a link to the corresponding official PDF file on govinfo.gov. This prototype edition of the daily Federal Register on FederalRegister.gov will remain an unofficial informational resource until the Administrative Committee of the Federal Register (ACFR) issues a regulation granting it official legal status. For complete information about, and access to, our official publications and services, go to About the Federal Register on NARA's archives.gov.
The OFR/GPO partnership is committed to presenting accurate and reliable regulatory information on FederalRegister.gov with the objective of establishing the XML-based Federal Register as an ACFR-sanctioned publication in the future. While every effort has been made to ensure that the material on FederalRegister.gov is accurately displayed, consistent with the official SGML-based PDF version on govinfo.gov, those relying on it for legal research should verify their results against an official edition of the Federal Register. Until the ACFR grants it official status, the XML rendition of the daily Federal Register on FederalRegister.gov does not provide legal notice to the public or judicial notice to the courts.
Federal Aviation Administration (FAA), DOT.
Notice of proposed rulemaking (NPRM).
The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Helicopters Model AS350B2 helicopters. This proposed AD was prompted by a report of magnetization on the solenoid valves for the three main servo-controls, the regulator block, and the tail servo-control due to a diode not properly installed in the hydraulic circuit. This proposed AD would require performing a cut-off test of the rear rotor actuator valve and depending on the results of the test, this AD would require performing corrective actions. The FAA is proposing this AD to address the unsafe condition on these products.
The FAA must receive comments on this NPRM by July 13, 2026.
You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:
AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2026-4646; 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, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above.
Material Incorporated by Reference:
Aryanna Sanchez, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 222-4058; email: aryanna.t.sanchez@faa.gov.
The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under ADDRESSES . Include “Docket No. FAA-2026-4646; Project Identifier MCAI-2025-01763-R” 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 amend 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 ( printed page 31674) 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.
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 Aryanna Sanchez, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590. Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking.
EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2025-0263, dated November 26, 2025; corrected December 9, 2025 (EASA AD 2025-0263) (also referred to as the MCAI), to correct an unsafe condition on certain Airbus Helicopters Model AS350 B2 helicopters. The MCAI states that during maintenance on a helicopter, magnetization was observed on the solenoid valves for the three main servo-controls, the regulator block, and the tail servo-control. The MCAI also states that after further investigation, it was determined that diode 43D2 was not installed in the hydraulic circuit.
The FAA is proposing this AD to prevent loss of the efficiency of the yaw load compensator and of hydraulic assistance for the three main servo-controls and the tail servo-control. The unsafe condition, if not addressed, could result in reduced control of the helicopter.
You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-4646.
The FAA reviewed EASA AD 2025-0263, which specifies procedures for performing a cut-off test, and, if any discrepancy is detected, replacing any affected diodes, or installing any missing diodes. 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.
These products have been approved by the civil aviation authority (CAA) of another country and are approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, that authority has notified the FAA of the unsafe condition described in the MCAI referenced above. 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.
This proposed AD would require accomplishing the actions specified in EASA AD 2025-0263, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this proposed AD.
In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some CAA ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. The FAA has been coordinating this process with manufacturers and CAAs. As a result, the FAA proposes to incorporate EASA AD 2025-0263 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2025-0263 in its entirety through that incorporation, except for any differences identified as exceptions in the regulatory text of this proposed AD. Using common terms that are the same as the heading of a particular section in EASA AD 2025-0263 does not mean that operators need comply only with that section. For example, where the AD requirement refers to “all required actions and compliance times,” compliance with this AD requirement is not limited to the section titled “Required Action(s) and Compliance Time(s)” in EASA AD 2025-0263. Material required by EASA AD 2025-0263 for compliance will be available at regulations.gov under Docket No. FAA-2026-4646 after the FAA final rule is published.
The FAA estimates that this AD, if adopted as proposed, would affect 12 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this proposed AD:
| Action | Labor cost | Parts cost | Cost per product | Cost on U.S. operators |
|---|---|---|---|---|
| Perform cut-off test | 3 work-hours × $85 per hour = $255 | $0 | $255 | $3,060 |
The FAA estimates the following costs to do any installations or replacements that would be required based on the results of the proposed test. The agency has no way of determining the number of helicopters that might need these installations or replacements.
| Action | Labor cost | Parts cost | Cost per product |
|---|---|---|---|
| Replace diode | 1 work-hour × $85 per hour = $85 | $180 | $265 |
| Install missing diode | 5 work-hours × $85 per hour = $425 | 1,000 | 1,425 |
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.
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.
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
Airbus Helicopters: Docket No. FAA-2026-4646; Project Identifier MCAI-2025-01763-R.
The FAA must receive comments on this airworthiness directive (AD) by July 13, 2026.
None.
This AD applies to all Airbus Helicopters Model AS350B2 helicopters as specified in, and in accordance with, European Union Aviation Safety Agency AD 2025-0263, dated November 26, 2025; corrected December 9, 2025 (EASA AD 2025-0263).
Joint Aircraft System Component (JASC) Code 2900, Hydraulic Power System.
This AD was prompted by a report of magnetization on the solenoid valves for the three main servo-controls, the regulator block, and the tail servo-control due to a diode not properly installed in the hydraulic circuit. The FAA is issuing this AD to prevent loss of the efficiency of the yaw load compensator and of hydraulic assistance for the three main servo-controls and the tail servo-control. The unsafe condition, if not addressed, could result in reduced control of the helicopter.
Comply with this AD within the compliance times specified, unless already done.
(g) Required Actions
Except as specified in paragraphs (h) and (i) of this AD: Comply with all required actions and compliance times specified in, and in accordance with, EASA AD 2025-0263.
(1) Where EASA AD 2025-0263 refers to its effective date, this AD requires using the effective date of this AD.
(2) Where EASA AD 2025-0263 requires compliance in terms of flight hours, this AD requires using hours time-in-service.
(3) Where the material referenced in EASA AD 2025-0263 specifies “remove the diode 43D2”, this AD requires replacing that text with “remove the diode 43D2 from service”.
(4) This AD does not adopt the “Remarks” section of EASA AD 2025-0263.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2025-0263 specifies to submit certain information to the manufacturer, this AD does not require that action.
(1) The Manager, International Validation 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 International Validation Branch, send it to the attention of the person identified in paragraph (k) of this AD and email to: AMOC@faa.gov.
(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.
(k) Additional Information
For more information about this AD, contact Aryanna Sanchez, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (817) 222-5110; email: aryanna.t.sanchez@faa.gov.
(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) European Union Aviation Safety Agency (EASA) AD 2025-0263, dated November 26, 2025; corrected December 9, 2025.
(ii) [Reserved]
(3) For EASA material identified in this AD, contact EASA Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999 000; email: ADs@easa.europa.eu; website: easa.europa.eu.
(4) You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 10101 Hillwood Parkway, Fort Worth, TX 76177. 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 fr.inspection@nara.gov.
Issued on May 22, 2026.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.
[FR Doc. 2026-10591 Filed 5-27-26; 8:45 am]
BILLING CODE 4910-13-P
This document has a comment period that ends in 34 days. (07/13/2026) View Comment Instructions