AD 2024-23-06

This AD is effective December 24, 2024.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-2011; 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, 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.

Eduardo Orozco-Duran, Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone: (562) 627-5264; email: eduardo.orozco-duran@faa.gov.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to MDHI Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters with a torque tube part number 369H7133-7 installed. The NPRM published in the Federal Register on August 8, 2024 (89 FR 64834). The NPRM was prompted by a report of a seized and damaged roller bearing assembly in the torque tube assembly of an MDHI Model MD369E helicopter. Since MDHI Model 369, 369A, 369D, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters have the same torque tube assembly installed, they are also affected by this unsafe condition. In the NPRM, the FAA proposed to require repetitively visually inspecting the torque tube for corrosion and cracks, repetitively visually inspecting the roller bearings for corrosion and degradation, performing a repetitive freedom-of-movement inspection of the torque tube assembly for binding or ratcheting, and corrective or additional action as necessary. The FAA is issuing this AD to address the unsafe condition on these products.

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

The FAA reviewed the relevant data 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 and clarifying two paragraph cross-references in the Required Actions section of this AD, paragraphs (g)(2)(iii)(A) and (g)(2)(iv), by replacing the text “paragraph (g)(2)(iii) of this AD” with “the introductory text of paragraph (g)(2)(iii) of this AD,” this AD is adopted as proposed in the NPRM.

The FAA estimates that this AD affects 353 helicopters of U.S. registry. Labor costs are estimated at $85 per work-hour. Based on these numbers, the FAA estimates the following costs to comply with this AD.

Visually inspecting the torque tube and roller bearings will take 1 work-hour for an estimated cost of $85 per helicopter and $30,005 for the U.S. fleet, per inspection cycle. Inspecting the torque tube assembly for freedom of movement will take 0.75 work-hour for an estimated cost of $64 per helicopter and $22,595 for U.S. fleet cost, per inspection cycle. If required, a more in-depth inspection of the roller bearings will take 0.25 work-hour for an estimated cost of $21 per helicopter, per instance.

If required, replacing a torque tube will take 6 work-hours and parts will cost $4,773 for an estimated cost of $5,283 per torque tube replacement. Replacing a roller bearing will take 6 work-hours and parts will cost $210 for an estimated cost of $720 per roller bearing replacement.

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.

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.

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

1. The authority citation for part 39 continues to read as follows:

2. The FAA amends § 39.13 by adding the following new airworthiness directive: