SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2024-02-55, Amendment 39-22674 (89 FR 14576, February 28, 2024) (AD 2024-02-55). AD 2024-02-55 applied to certain BTCL Model 505 helicopters. AD 2024-02-55 required accomplishing initial and recurring inspections of the vertical stabilizer top end cap assembly, and if a crack is found, replacement of the top end cap. The FAA issued AD 2024-02-55 to address cracking in the vertical stabilizer top end cap assembly. This condition, if not addressed, could result in the antenna or tuning weight departing from the helicopter and impacting and damaging the tail rotor, which could result in the loss of directional control of the helicopter.

The NPRM was published in the Federal Register on April 8, 2026 (91 FR 17772). The NPRM was prompted by Transport Canada AD CF-2025-32, dated July 2, 2025 (Transport Canada AD CF-2025-32) (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states that a new one-piece vertical stabilizer machined top end cap assembly, having part number (P/N) SLS-030-701-149, was implemented into the Bell 505 production line, and a new machined top end cap assembly, P/N SLS-704-701-101, was developed as a replacement for the top end cap assembly P/N SLS-030-701-125 that is currently in service. The MCAI requires repetitive inspections of the vertical stabilizer top end cap assembly until the required replacement with a new machined top end cap assembly, P/N SLS-704-701-101, which is considered terminating action for the repetitive inspections.

In the NPRM, the FAA proposed to continue to require the inspection requirements of AD 2024-02-55 and proposed to limit the applicability to exclude certain serial numbered BTCL Model 505 helicopters with an improved design vertical stabilizer top end cap installed at production. In the NPRM, the FAA also proposed to require replacing the vertical stabilizer top end cap assembly with an improved design top end cap assembly, which would constitute a terminating action for the recurring detailed visual inspections.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2026-3477.

Discussion of Final Airworthiness Directive

Comments

The FAA received no comments on the NPRM or on the determination of the costs.

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 Transport Canada AD CF-2025-32, which specifies procedures for accomplishing a one-time detailed visual inspection of the vertical stabilizer top end cap assembly for cracking; replacing any cracked vertical stabilizer top end cap assembly; repetitively inspecting vertical stabilizer top end cap assembly P/N SLS-030-701-125; and replacing vertical stabilizer top end cap assembly P/N SLS-030-701-125 with vertical stabilizer top end cap assembly P/N SLS-704-701-101.

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

Where the material referenced in Transport Canada AD CF-2025-32 specifies to contact the manufacturer if the drilled holes can no longer go beyond the allowable dimensions, this AD requires corrective action to be done in accordance with a method approved by the Manager, International Validation Branch, FAA; or Transport Canada; or Bell Textron Canada Limited Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. ( printed page 47955)

Costs of Compliance

The FAA estimates that this AD affects 150 helicopters of U.S. registry.

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

The FAA has included all known costs in its cost estimate. According to the manufacturer, however, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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: