The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. This AD was prompted by the det...
[Docket No. FAA-2026-4657; Project Identifier MCAI-2024-00383-R; Amendment 39-23481; AD 2026-20-08]
RIN 2120-AA64
AGENCY:
Federal Aviation Administration (FAA), DOT.
ACTION:
Final rule.
SUMMARY:
The FAA is adopting a new airworthiness directive (AD) for all Airbus Helicopters Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. This AD was prompted by the determination that the tail rotor drive fan wheels (fan wheels) and the impeller second stage have been incorrectly identified during production. This AD requires verifying the serial number and amendment of the log cards of the affected parts, and depending on the findings, performing a one-time borescope inspection to verify consistency between the log cards and the affected parts. Depending on the results of the inspection, this AD requires replacing or re-identifying certain parts. This AD also prohibits the installation of certain fan wheels and impeller second stages on any helicopter. The FAA is issuing this AD to address the unsafe conditions on these products.
DATES:
This AD is effective November 5, 2026.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of November 5, 2026.
ADDRESSES:
AD Docket:
You may examine the AD docket at
regulations.gov
under Docket No.FAA-2026-4657; 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.
Material Incorporated by Reference:
For European Union Aviation Safety Agency (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.
You may find the EASA material on the EASA website at
ad.easa.europa.eu.
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. It is also available atregulations.gov
under Docket No. FAA-2026-4657.
FOR FURTHER INFORMATION CONTACT:
Andrew Gronau, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (847) 294-7378; email:
andrew.s.gronau@faa.gov.
SUPPLEMENTARY INFORMATION:
( printed page 62308)
Background
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Airbus Helicopters Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. The NPRM was published in the
Federal Register
on June 18, 2026 (91 FR 36771). The NPRM was prompted by an MCAI issued by EASA, which is the Technical Agent for the Member States of the European Union. EASA issued EASA AD 2024-0127, dated July 3, 2024 (EASA AD 2024-0127) (also referred to as the MCAI). The MCAI states that it was determined that the fan wheel part number (P/N) 704A33691014 amdt [amendment] C and the impeller second stage P/N 704A33691015 amdt C have been incorrectly identified in production. Incorrect identification may cause the loss of traceability of the affected parts, which could lead to required inspections not being accomplished. The unsafe condition, if not addressed, could lead to undetected fatigue failure of the affected parts and result in loss of control of the helicopter.
In the NPRM, the FAA proposed to require verifying the serial number and amendment of the log cards of the affected parts, and depending on the findings, performing a one-time borescope inspection to verify consistency between the log cards and the affected parts, and depending on the inspection results, the FAA proposed to require replacing or re-identifying certain parts. The FAA is issuing this AD to address the unsafe conditions on these products.
You may examine the MCAI in the AD docket at
regulations.gov
under Docket No. FAA-2026-4657.
Discussion of Final Airworthiness Directive
Comments
The FAA received one comment from an anonymous commenter on the NPRM. The commenter's viewpoint was general in nature without a suggestion specific to the AD and did not make a request the FAA can act on. Therefore, this comment is considered outside the scope of this AD.
Conclusion
These products have been approved by the civil aviation authority 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.
Material Incorporated by Reference Under 1 CFR Part 51
The FAA reviewed EASA AD 2024-0127, which specifies procedures for verifying the helicopter's existing log card to determine whether an affected fan wheel and impeller second stage are installed. Depending on the results, EASA AD 2024-0127 specifies procedures for performing a borescope inspection of the affected parts for further verification and either replacing affected parts or re-identifying the parts and amending their log cards. EASA AD 2024-0127 also prohibits installing an affected fan wheel or impeller second stage 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
ADDRESSES
section.
Costs of Compliance
The FAA estimates that this AD affects four helicopters of U.S. registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs
Action
Labor cost
Parts cost
Cost per
product
Cost on U.S.
operators
Review log card
1 work-hour × $85 per hour = $85
$0
$85
$340
The FAA estimates the following costs to do any replacements that will be required based on the results of the inspection. The agency has no way of determining the number of helicopters that might need these replacements:
On-Condition Costs
Action
Labor cost
Parts cost
Cost per
product
Perform borescope inspection of the fan wheel
1 work-hour × $85 per hour = $85
$0
$85
Perform borescope inspection of the impeller second stage
1 work-hour × $85 per hour = $85
0
85
Replace fan wheel
2 work-hours × $85 per hour = $170
1,534
1,704
Replace impeller second stage
2 work-hours × $85 per hour = $170
1,219
1,389
Perform balance of tail rotor drive shaft
2 work-hours × $85 per hour = $170
0
170
Re-identify the fan wheel or the impeller second stage
1 work-hour × $85 per hour = $85
0
85
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
( printed page 62309)
unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
Regulatory Findings
This AD will not have federalism implications under Executive Order 13132. This AD will 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 that this AD:
(2) Will not affect intrastate aviation in Alaska, and
(3) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
This AD was prompted by the determination that the tail rotor drive fan wheel and impeller second stage have been incorrectly identified during production. The FAA is issuing this AD to detect and address incorrect identification of the affected parts. The unsafe condition, if not addressed, may cause the loss of traceability of the affected parts, which could lead to undetected fatigue failure of the affected parts and result in loss of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
(g) Requirements
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, European Union Aviation Safety Agency AD 2024-0127, dated July 3, 2024 (EASA AD 2024-0127).
(h) Exceptions to EASA AD 2024-0127
(1) Where EASA AD 2024-0127 refers to its effective date, this AD requires using the effective date of this AD.
(2) Where EASA AD 2024-0127 requires compliance in terms of flight hours, this AD requires using hours time-in-service.
(3) Where EASA AD 2024-0127 defines “affected part”, this AD requires replacing that text with “tail rotor drive fan wheel having part number (P/N) 704A33691014 amdt [amendment] C and impeller second stage P/N 704A33691015 amdt [amendment] C, and a serial number (S/N), as identified in the Log Card, listed as `S/N affected' in section 4.5 or 4.6 of the accomplishment procedure of Airbus Helicopters Alert Service Bulletin ASB AS355-65-00-0001, Issue 001 dated May 27, 2024”.
(4) This AD does not adopt the “Remarks” section of EASA AD 2024-0127.
(i) No Reporting Requirement
Although the material referenced in EASA AD 2024-0127 specifies to submit certain information to the manufacturer, this AD does not require that action.
(j) Alternative Methods of Compliance (AMOCs)
(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 Andrew Gronau, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (847) 294-7378; email:
andrew.s.gronau@faa.gov.
(l) Material Incorporated by Reference
(1) The Director of the Federal Register approved the incorporation by reference 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 2024-0127, dated July 3, 2024.
(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.
You may find the EASA material on the EASA website at
ad.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.