SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2023-25-14, Amendment 39-22641 (88 FR 89568, December 28, 2023) (AD 2023-25-14). AD 2023-25-14 applied to certain Airbus Helicopters Model EC130T2 helicopters. AD 2023-25-14 required repetitively checking the balancing of the tail rotor drive shaft by measuring the vibration level. Depending on the results, AD 2023-25-14 required replacing certain parts with new parts. AD 2023-25-14 also prohibited installing certain part-numbered tail rotor drive shafts on any helicopter unless its requirements are met. The FAA issued AD 2023-25-14 to address an excessive vibration level on the tail rotor drive shaft. The unsafe condition, if not addressed, could result in failure of the tail rotor drive shaft and loss of yaw control of the helicopter.

The NPRM was published in the Federal Register on May 22, 2026 (91 FR 30257). The NPRM was prompted by EASA AD 2024-0144, dated July 19, 2024 (EASA AD 2024-0144) (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 the manufacturer developed a modification consisting of a new rear rotor drive shaft, a new sliding flange, and a new equipped splined sleeve, and that while these parts are less susceptible to cracks, insufficient data is available to treat them as terminating action for that AD's repetitive actions. In addition, EASA AD 2024-0144 expands the list of affected part numbers to include the new modified parts.

In the NPRM, the FAA proposed to require installing this modification and repetitively inspecting the vibration level of the tail rotor drive shaft. In the NPRM, the FAA also proposed to prohibit the installation of certain parts and prohibit the performance of a balance correction unless certain requirements are met.

The FAA is issuing this AD to address the unsafe condition on these products.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-4644.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from an anonymous commenter who restated the applicability of the AD. The FAA infers that the commenter supported the NPRM without change.

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 2024-0144, which specifies procedures for repetitively checking the balancing of the tail rotor drive shaft by measuring the vibration level and, depending on the results, replacing certain parts with either used, new, or modified parts. EASA AD 2024-0144 also prohibits performing a balance correction unless this action is performed concurrently with replacing certain parts. If a balance correction has already been performed independently of replacing those parts, EASA AD 2024-0144 specifies contacting Airbus Helicopters to obtain approved instructions and accomplishing those instructions. EASA AD 2024-0144 also specifies reporting the vibration measurements to Airbus Helicopters and installing modified rear drive shaft, sliding flange, and equipped splined sleeve parts. Lastly, EASA AD 2024-0144 prohibits installing certain part-numbered tail rotor drive shafts, sliding flanges, or equipped splined sleeves on any helicopter.

This material is reasonably available because the interested parties have ( printed page 52495) 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

Where EASA AD states to contact Airbus Helicopters, this AD would require contacting either the Manager, International Validation Branch, FAA; or EASA; or Airbus Helicopters' EASA Design Organization Approval (DOA).

Interim Action

The FAA considers that this AD is an interim action. If final action is later identified, the FAA might consider further rulemaking then.

Costs of Compliance

The FAA estimates that this AD affects 108 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 replacements 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 these replacements:

For helicopters that accomplished a balance correction in accordance with the instructions of the applicable AMM before the effective date of this AD, except those that accomplished a balance correction before the next flight after installing a new (zero total hours time-in-service) sliding flange and a new (zero total hours time-in-service) equipped splined sleeve, the corrective action that may be needed could vary significantly from helicopter to helicopter. The FAA has no data to determine the costs to accomplish the corrective action or the number of helicopters that may require 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

The FAA has determined that 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:

(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: