SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2024-23-06, Amendment 39-22885 (89 FR 91248, November 19, 2024) (AD 2024-23-06). AD 2024-23-06 applied to certain MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters. AD 2024-23-06 was prompted by a report of a seized and damaged roller bearing assembly in the torque tube assembly of an MD Helicopters, LLC Model 369E helicopter. AD 2024-23-06 required repetitively inspecting the torque tube assembly and roller bearings, and depending on the results, replacing parts or accomplishing additional inspections.

The NPRM was published in the Federal Register on November 18, 2025 (90 FR 51596). The NPRM was prompted by a report that additional torque tube assemblies are affected by the same unsafe condition addressed in AD 2024-23-06 and should be included in the AD action. In the NPRM, the FAA proposed to continue to require the actions of AD 2024-23-06, and also proposed to expand the applicability to include all MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, regardless of the torque tube part number. The FAA is issuing this AD to prevent failure of the torque tube assembly, which, if not addressed, could result in reduced controllability and loss of control of the helicopter.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Citizens Rulemaking Alliance. The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Justify Forgoing Notice and Comment or Issue an NPRM

The Citizens Rulemaking Alliance requested that, absent justification for finding good cause to bypass notice and comment procedures, the FAA either convert this action to an NPRM with a 30-day comment period or defer the effective date by 30 to 60 days while maintaining a parallel safety alert or special airworthiness information bulletin and highlighting voluntary compliance with the service information. The commenter asserted the FAA has not adequately justified use of the good cause exemption to bypass notice and comment and the 30-day delayed effective date.

The FAA notes the comment was submitted in response to an NPRM for which the FAA provided a 45-day comment period. This final rule is effective 35 days after its publication in the Federal Register . Therefore, the FAA did not change this AD as a result of this comment.

Request To Supplement the AD Docket With Supporting Data

The Citizens Rulemaking Alliance requested that the FAA add to the AD docket the FAA's risk assessment, the background report data, the dates of the triggering service information and any foreign authority AD, and a summary of alternatives considered and rejected for safety reasons. The commenter stated that this will allow commenters to address safety tradeoffs while preserving urgent mitigation if warranted.

The FAA has assessed and disclosed the background and basis for this rulemaking in the preamble of the NPRM, including a discussion of the previous AD, a description of the unsafe condition, and the FAA's rationale for the required actions on additional torque tube assemblies. This information was available to the public during the 45-day comment period provided by the NPRM.

The FAA evaluated the alternative of not promulgating this AD but ultimately determined that this alternative would create a significant safety hazard. Relying on voluntary compliance or existing requirements would leave the unsafe condition unaddressed and would not ensure an acceptable level of safety. Accordingly, the FAA has determined that promulgating this AD is necessary to ensure an acceptable level of safety.

Since the FAA has assessed and disclosed the basis for this rulemaking in the preamble of the NPRM, there is no service material or foreign authority AD related to this rulemaking action, and the commenter did not provide additional safety data for the FAA to consider in its analysis, it is not necessary to provide additional information in the AD docket.

Request To Comply With the Paperwork Reduction Act (PRA)

The Citizens Rulemaking Alliance requested that the FAA revise the proposed AD to comply with the PRA if reporting is required, or remove any reporting provisions and stay enforcement until PRA requirements are satisfied. The commenter stated that the PRA requires providing the applicable Office of Management and Budget (OMB) control number(s), required PRA statements, and burden estimates in the AD and docket. If reporting is not required, the commenter requested the FAA clarify that in the AD.

The FAA notes that this AD does not require reporting. If an AD were to require reporting, the preamble of the AD would include a paragraph titled “Paperwork Reduction Act” that would provide the applicable OMB control number, required PRA statements, and the estimated time to collect the required information (burden). Any costs associated with the reporting requirement would be included in the Costs of Compliance section in the preamble of the AD. Therefore, the FAA did not change this AD as a result of this comment. ( printed page 58367)

Request To Make Incorporation by Reference (IBR) Materials Reasonably Available

The Citizens Rulemaking Alliance stated that the FAA's current practices for IBR frequently fail to meet the legal and regulatory standards for reasonable availability. The commenter called on the FAA to guarantee that all IBR materials are easily and freely accessible to the public and affected parties for both commenting and compliance purposes. They also requested that this access be documented in the rulemaking record. Further, the commenter requested that, if reasonable availability cannot be assured, enforcement of the incorporated by reference requirements be deferred until it is assured.

The FAA notes that this AD does not incorporate by reference any material. All required actions and compliance times are contained within the regulatory text of this AD. Therefore, the FAA did not change this AD as a result of this comment.

Request To Consider Impact on Small Entities

The Citizens Rulemaking Alliance requested that the FAA either provide the factual basis for its Regulatory Flexibility Act (RFA) certification that the AD will not have a significant economic impact on a substantial number of small entities or prepare an initial regulatory flexibility analysis and seek input from the Office of Advocacy from the Small Business Administration (SBA).

The FAA has considered the AD's impact on small businesses and provides the following analysis.

The Regulatory Flexibility Act of 1980, Public Law 96-354, 94 Stat. 1164 (5 U.S.C. 601-612), as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (Public Law 104-121, 110 Stat. 857, Mar. 29, 1996) and the Small Business Jobs Act of 2010 (Public Law 111-240, 124 Stat. 2504, Sept. 27, 2010), requires Federal agencies to consider the effects of the regulatory action on small business and other small entities and to minimize any significant economic impact. The term “small entities” comprises small businesses and not-for-profit organizations that are independently owned and operated and are not dominant in their fields, and governmental jurisdictions with populations of less than 50,000.

Small Entities to Which This AD Applies

The FAA used the definition of small entities in the RFA for this analysis. The RFA defines small entities as small businesses, small governmental jurisdictions, or small organizations. In 5 U.S.C. 601(3), the RFA defines “small business” to have the same meaning as “small business concern” under section 3 of the Small Business Act. The Small Business Act authorizes the SBA to define “small business” by issuing regulations.

The SBA has established size standards for various types of economic activities, or industries, under the North American Industry Classification System (NAICS). These size standards generally define small businesses based on the number of employees or annual receipts. The following table provides the SBA size standards for all industries with at least one entity ^[1] impacted by this AD. Note that the SBA definition of a small business applies to the parent company and all affiliates as a single entity.

To identify small entities, the FAA first identified the primary NAICS of the entity or parent company, and then used data from different sources ( e.g., company annual reports, Bureau of Transportation Statistics) to determine whether the entity meets the applicable size standard. The FAA provides the estimated number of small entities affected by this AD: ( printed page 58369)

Projected Reporting, Recordkeeping, and Other Compliance Requirements

The FAA estimates affected entities will incur an inspection cost of $149 per inspection cycle, with an average of 7 inspection cycles per year. FAA analyzes the cost of inspection of $1,043 as the low-case for each small entity. Based upon the results of the inspections, operators could incur up to 3 on-condition costs of $6,024. If an operator were to incur all inspection and on-condition costs, FAA estimates each operator would incur $7,067 per helicopter annually. The FAA has no way to determine if each helicopter will require these on-condition costs. The high-case includes both inspection and on-condition costs for each small entity. The following table presents the small entity case burdens average percentage for compliance based on the average annual revenue by each NAICS industry.

Significant Alternatives Considered

The FAA evaluated the alternative of not promulgating this AD but ultimately deemed that this alternative would create a significant safety hazard. Since the issuance of AD 2024-23-06, which affected certain MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters, it has been determined that the risk of failure of the torque tube assembly extends to additional torque tube assemblies. Relying on the existing requirements would leave these additional torque tube assemblies unmonitored. By expanding the applicability, this AD addresses the unsafe condition and prevents potential failure, ensuring a level of safety that the alternative of no action could not provide.

Conclusion

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, replacement of the RFA certification with a final regulatory flexibility analysis, a change in the Costs of Compliance section (from 353 helicopters to 680 helicopters and corresponding cost changes), and any other changes described previously, this AD is adopted as proposed in the NPRM. None of the changes will increase the economic burden on any operator.

Costs of Compliance

The FAA estimates that this AD affects 680 helicopters of U.S. registry. The FAA estimates the following costs to comply with this AD: ( printed page 58372)

The FAA estimates the following costs to do any on-condition actions that would be required based on the results of the inspections. The agency has no way of determining the number of helicopters that might need these on-condition actions:

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:

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

(2) Will not affect intrastate aviation in Alaska.

The Amendment

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