2026-19729: Airworthiness Directives; Airbus Helicopters

Federal Register, Volume 91 Issue 186 (Monday, September 28, 2026) [Federal Register Volume 91, Number 186 (Monday, September 28, 2026)] [Proposed Rules] [Pages 61164-61166] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 2026-19729] ======================================================================== Proposed Rules Federal Register ________________________________________________________________________ This section of the FEDERAL REGISTER contains notices to the public of the proposed issuance of rules and regulations. The purpose of these notices is to give interested persons an opportunity to participate in the rule making prior to the adoption of the final rules. ======================================================================== Federal Register / Vol. 91, No. 186 / Monday, September 28, 2026 / Proposed Rules [[Page 61164]] DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA-2026-11787; Project Identifier MCAI-2026-00249-R] RIN 2120-AA64 Airworthiness Directives; Airbus Helicopters

Agency

Federal Aviation Administration (FAA), DOT.

Action

Notice of proposed rulemaking (NPRM). -----------------------------------------------------------------------

Summary

The FAA proposes to adopt a new airworthiness directive (AD) for all Airbus Helicopters Model AS 365 N2, AS 365 N3, EC 155 B, EC 155 B1, SA 365 N, and SA 365 N1 helicopters. This proposed AD was prompted by gaps between the seals and engine cowling, which were found during an investigation related to an engine compartment fire. Gaps between the seals and engine cowling could cause inadequate sealing of the engine compartment firewalls leading to fire propagation between engine compartments and reduced effectiveness of the extinguishing agent. This proposed AD would require modifying the engine compartment firewalls by installing angle-brackets along the firewalls. The FAA is proposing this AD to address the unsafe condition on these products.

Dates

The FAA must receive comments on this NPRM by November 12, 2026.

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-2026-11787; 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: For European Union Aviation Safety Agency (EASA) material identified in this proposed AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999 000; email: [email protected]; website: easa.europa.eu. You may find this material on the EASA website at ad.easa.europa.eu. It is also available at regulations.gov under Docket No. FAA-2026-11787. 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.

For Further Information Contact

Evan Weaver, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (316) 944-8910; 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 using a method listed under ADDRESSES. Include ``Docket No. FAA-2026-11787; Project Identifier MCAI-2026-00249-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 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 Evan Weaver, 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. Background EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2026-0056, dated March 16, 2026 (EASA AD 2026-0056) (also referred to as the MCAI), to correct an unsafe condition on all Airbus Helicopters Model SA 365 N, SA 365 N1, AS 365 N2, AS 365 N3, EC 155 B, and EC 155 B1 helicopters. The MCAI states that during an investigation following an engine compartment fire, gaps were identified between the seals and engine cowlings. Analysis showed that some seals along the firewalls did not fully compress against the engine cowlings. Thus, the seal is not fully completed between the main gear box, the left engine compartment and the right engine compartment. Without a full seal, the extinguishing agent is not contained within the compartment when the pilot operates the engine fire extinguisher. The FAA is proposing this AD to prevent fire propagation between engine compartments and the reduced [[Page 61165]] effectiveness of the extinguishing agent due to inadequate sealing of the engine compartment firewalls. The unsafe condition, if not addressed, could allow fire propagation from one engine compartment to another and reduce the effectiveness of the extinguishing agent in the event of an engine fire, which could result in loss of control of the helicopter. You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-11787. Material Incorporated by Reference Under 1 CFR Part 51 The FAA reviewed EASA AD 2026-0056, which specifies procedures for modifying the engine compartment firewalls by installing angle-brackets along the firewalls to improve sealing between the seals and engine cowlings. 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. FAA's Determination 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. Proposed AD Requirements in This NPRM This proposed AD would require accomplishing the actions specified in EASA AD 2026-0056, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this proposed AD. Explanation of Required Compliance Information 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 2026-0056 by reference in the FAA final rule. This proposed AD would, therefore, require compliance with EASA AD 2026-0056 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 2026-0056 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 2026-0056. Material required by EASA AD 2026-0056 for compliance will be available at regulations.gov under Docket No. FAA-2026-11787 after the FAA final rule is published. Costs of Compliance The FAA estimates that this AD, if adopted as proposed, would affect 43 helicopters of U.S. registry. The FAA estimates the following costs to comply with this proposed AD: Estimated Costs ---------------------------------------------------------------------------------------------------------------- Cost on U.S. Action Labor cost Parts cost Cost per product operators ---------------------------------------------------------------------------------------------------------------- Modification of engine 6 work-hours x $85 Up to $32,360...... Up to $32,870...... $1,413,410 compartment firewalls. per hour = $510. ---------------------------------------------------------------------------------------------------------------- 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 0