SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Airbus Helicopters Model AS350B, AS350BA, AS350B1, AS350B2, AS350B3, AS350D, EC130B4, and EC130T2 helicopters. The NPRM was published in the Federal Register on May 15, 2026 (91 FR 27873). The NPRM was prompted by EASA AD 2023-0127, dated June 27, 2023 (EASA AD 2023-0127) (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 on the final assembly line, the engine flange on the MGB engine coupling may have been installed inverted. ( printed page 50692)

In the NPRM, the FAA proposed to require inspecting the MGB engine coupling for correct installation and, depending on the results, corrective actions.

The FAA is issuing this AD to detect and correct the inverted installation of the engine flange on the MGB engine coupling. The unsafe condition, if not detected and corrected, could result in the loss of power transmission to the MGB and the main rotor and lead to loss of control of the helicopter.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-4638.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from one commenter, Papillon Airways (Papillon). The following presents the comment received on the NPRM and the FAA's response to the comment.

Request To Change the Applicability

Papillon requested the FAA revise the applicability of the NPRM, to apply not only to the production date of the helicopters but also that the NPRM apply to helicopters with less than 3,500 total flight hours. Papillon stated the date ranges are too broad and they do not address high usage aircraft. Papillon also stated that aircraft with more than 3,500 flight hours have likely already replaced the engine and gearboxes [MGB] and would therefore no longer be affected by the unsafe condition.

The FAA disagrees with revising the applicability of this final rule. The FAA is unable to determine how many helicopters may have replaced the MGBs or engines before 3,500 total hours time-in-service (TIS) or how many helicopters may not have replaced the MGB or engine before exceeding 3,500 total hours TIS. The FAA acknowledges that a majority of the MGBs may have been replaced. Thus, adopting the MCAI applicability ensures that all helicopters that may be affected are included in this final rule. The FAA did not change this AD as a result of this comment.

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 2023-0127, which specifies procedures for a one-time inspection of the MGB engine coupling for correct installation. Depending on the results, EASA AD 2023-0127 specifies installing a correctly assembled engine flange or a new engine flange. EASA AD 2023-0127 also specifies reporting the inspection results to the manufacturer. 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.

Differences Between This AD and the MCAI

The MCAI applies to Airbus Helicopters Model AS350BB helicopter, whereas this AD does not because that model does not have an FAA type certificate.

Costs of Compliance

The FAA estimates that this AD affects 4,102 helicopters of U.S. registry.

The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any corrective actions that would be required based on the results of the inspection. The agency has no way of determining the number of helicopters that might need this corrective action:

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

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: ( printed page 50693)

(1) Is not a “significant regulatory action” under Executive Order 12866,

(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.

The Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: