Airworthiness Directives; Airbus Helicopters

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-1735; Project Identifier MCAI-2024-00408-R; Amendment 39-23199; AD 2025-24-04]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; Airbus Helicopters</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA is superseding Airworthiness Directive (AD) 2021-20-16, which applied to all Airbus Helicopters Model AS355E, AS 355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters and certain Model AS 350B3 helicopters. AD 2021-20-16 required repetitive cleaning and visual and detailed inspections of the right-hand side of the vertical fin spar and vertical fin upper attachments for discrepancies (cracking) with corrective action, if necessary. Since the FAA issued AD 2021-20-16, Airbus Helicopters developed a modification of the upper fin assembly. This AD requires the same actions as AD 2021-20-16 and replacement of the upper fin assembly with a modified upper fin assembly, which constitutes a terminating action for the repetitive inspections. The FAA is issuing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This AD is effective January 12, 2026. The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of January 12, 2026. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-1735; 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 final rule, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. <E T="03">Material Incorporated by Reference:</E> • For European Union Aviation Agency (EASA) material identified in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; phone: +49 221 8999 000; email: <E T="03">ADs@easa.europa.eu;</E> website: <E T="03">easa.europa.eu.</E> You may find the EASA material on the EASA website at <E T="03">ad.easa.europa.eu.</E> • You may view this material at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room 6N-321, Fort Worth, TX 76177. For information on the availability of this material at the FAA, call (817) 222-5110. It is also available at <E T="03">regulations.gov</E> under Docket No. FAA-2025-1735. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Steven Warwick, Aviation Safety Engineer, FAA, 1600 Stewart Ave., Suite 410, Westbury, NY 11590; phone: (817) 222-5225; email: <E T="03">Steven.R.Warwick@faa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Background</HD> The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2021-20-16, Amendment 39-21754 (86 FR 57550, dated October 18, 2021) (AD 2021-20-16). AD 2021-20-16 applied to Airbus Helicopters Model AS355E, AS 355-F, AS 355-F1, AS355F2, AS355N, and AS355NP helicopters, all serial numbers, and Model AS 350B3 helicopters, all serial numbers except those that have Airbus Helicopters Modification 073148 in production. AD 2021-20-16 required repetitive cleaning and detailed inspections for cracking of the vertical fin spar and vertical fin upper attachments, and corrective action if necessary. The FAA issued AD 2021-20-16 to address cracking in the spar of the upper part of the vertical fin and fractures in the front attachment screws. The NPRM was published in the <E T="04">Federal Register</E> on August 21, 2025 (90 FR 40786). The NPRM was prompted by EASA AD 2024-0139, dated July 12, 2024 (EASA AD 2024-0139) (also referred to as the MCAI), issued by EASA, which is the Technical Agent for the Member States of the European Union. The MCAI states that after a further occurrence of a crack on a Model AS355NP helicopter, EASA concluded there was a need to temporarily reduce the never-exceed-speed (V <E T="52">NE</E> ) for all AS355 helicopters. In addition, Airbus Helicopters developed a reinforced upper fin assembly and published service information that provides instructions for this modification. EASA AD 2024-0139 retains the repetitive inspections and V <E T="52">NE</E> limitations in its previous ADs and also requires modification of the helicopter with the reinforced upper fin assembly, which is the terminating action for the inspections and limitations. In the NPRM, the FAA proposed to require the same actions as AD 2021-20-16 and proposed to require replacement of the upper fin assembly with a modified upper fin assembly, which constitutes a terminating action for the repetitive inspections and limitations. The FAA is issuing this AD to address cracking in the upper fin spar and fracturing of the front attachment screws. The unsafe condition, if not addressed, could result in in-flight separation of the upper part of the vertical fin and consequent loss of control of the helicopter. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-1735. <HD SOURCE="HD1">Discussion of Final Airworthiness Directive</HD> <HD SOURCE="HD1">Comments</HD> The FAA received a comment from one individual who disagreed with the practice of relying on manufacturer-issued and foreign regulatory documents that are not fully integrated into the rule text. The following presents the comment received on the NPRM and the FAA's response to the comment. <HD SOURCE="HD1">Request To Incorporate Requirements Directly Into the AD</HD> The individual commenter requested that the FAA AD become a stand-alone document. The individual commented that relying on EASA's AD as the base document, and providing exceptions in the FAA's rule, makes the requirements unclear and confusing. The commenter further stated that the AD should comply with plain language guidelines in FAA Order 1000.36. The FAA disagrees with the request. In the FAA's ongoing efforts to improve the efficiency of the AD process, the FAA developed a process to use some civil aviation authority (CAA) ADs as the primary source of information for compliance with requirements for corresponding FAA ADs. This AD incorporates EASA AD 2024-0139 by reference. Incorporating information by reference is a common method of federal rulemaking, that is explicitly permitted under 1 CFR 51. As stated in the Incorporation by Reference Handbook, June 2023 Edition, incorporation of relevant, usually technical information (such as the MCAI) promotes efficiency. The commenter did not identify a provision of FAA Order 1000.36A that the IBR practice violates, and none are apparent to the FAA. The complete inspection method, measurable thresholds, and corrective actions are included in EASA AD 2024-0139 and the material referenced in EASA AD 2024-0139, which are available at <E T="03">regulations.gov</E> under the Docket No. for this AD, FAA-2025-1735. The FAA has not changed this AD in this regard. <HD SOURCE="HD1">Conclusion</HD> These products have been approved by the 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 reviewed the relevant data, considered any comments received, and determined that air safety requires adopting this AD as proposed. Accordingly, the FAA is issuing this AD to address the unsafe condition on these products. Except for minor editorial changes, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> The FAA reviewed EASA AD 2024-0139, which specifies procedures for amending the rotorcraft flight manual (RFM) and installing a placard to add a speed limitation. EASA AD 2024-0139 allows exceeding the speed limitation on certain maintenance flights and specifies accomplishing an inspection after each flight where the speed is exceeded. EASA AD 2024-0139 also requires repetitively inspecting the right-hand external side around the two top screws of certain upper fin spars for a crack. EASA AD 2024-0139 specifies that installing an upper fin assembly P/N 355A14-0522-1751 constitutes terminating action for the repetitive inspection requirements and the speed limitations. Lastly, EASA AD 2024-0139 prohibits installing affected upper fin assemblies on any helicopter. 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 <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">Differences Between This AD and the MCAI Referenced Material</HD> While the material referenced in EASA AD 2024-0139 requires accomplishing dye penetrant inspections (DPI), this AD requires a DPI if the affected part has previously been inspected by a DPI method; otherwise, this AD requires a fluorescent penetrant inspection (FPI). Where EASA AD 2024-0139 and the material referenced in EASA AD 2024-0139 specifies contacting Airbus Helicopters for repair instructions, this AD requires using a method approved by the FAA, EASA, or Airbus Helicopters' EASA Design Organization Approval. EASA AD 2024-0139 requires informing all flight ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 23k characters. 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