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 all De Havilland Aircraft of Canada Limited Model DHC-8 airplanes. The NPRM was published in the Federal Register on September 29, 2025 (90 FR 46538). The NPRM was prompted by AD CF-2020-06R1, dated January 7, 2021 (also referred to as the MCAI), issued by Transport Canada, which is the aviation authority for Canada. The MCAI states there were findings related to cracked barrel nuts at the wing front spar and horizontal stabilizer to vertical stabilizer joint. For those locations, Transport Canada issued Transport Canada AD CF-2011-24R1 (which corresponds to FAA AD 2019-20-09, Amendment 39-19762 (84 FR 56680, October 23, 2019)) and Transport Canada AD CF-2015-13R1 (which corresponds to FAA AD 2018-22-03, Amendment 39-19476 (83 FR 53563, October 24, 2018)) to address the unsafe condition. Barrel nuts are also installed in other locations on the airplane. An investigation determined that the cracking is caused by corrosion from inadequate cadmium plating on the barrel nuts. This condition, if not addressed, could result in failed barrel nuts that could compromise the structural integrity of the affected joints ( i.e., of the airplane) and could lead to loss of control of the airplane.

In the NPRM, the FAA proposed to require repetitive inspections for cracking and corrosion of the affected barrel nuts and applicable corrective actions. 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-2025-2558.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from the Air Line Pilots Association, International (ALPA) who supported the NPRM without change.

The FAA received additional 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 commenter requested that the FAA provide its justification for finding good cause to bypass notice and comment procedures and either convert this action to an NPRM, or stay the effective date to allow comments. 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, no change to this AD is necessary.

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

The Citizens Rulemaking Alliance requested the FAA ensure that IBR materials or summaries of them are in the public docket and are accessible for free to the public and affected parties for both commenting and compliance purposes. The commenter stated that the FAA's rule must comply with statutory and regulatory requirements for the reasonable availability of material incorporated by reference.

The FAA's practices comply with 5 U.S.C. 552(a) of the Administrative Procedure Act and 1 CFR part 51. The FAA makes IBR materials available in the AD docket when the final rule is published in the Federal Register , following formal approval of the IBR by the Office of the Federal Register. Materials may only be posted before the final rule's publication if they are already publicly available or if there is written consent from the owner of the IBR material. All relevant materials incorporated by reference will be ( printed page 33585) accessible in the AD docket on Regulations.gov, which the public can access without registration or fees.

The FAA also provides summaries and access details in the preamble and regulatory text, makes materials available for inspection at FAA and National Archives and Records Administration (NARA) offices, offers publisher contact information, and obtains formal IBR approval from the Office of the Federal Register. These efforts are intended to ensure that all IBR materials meet the “reasonably available” standard required by 1 CFR part 51. The FAA did not change this AD as a result of this comment.

Request To Comply With the Paperwork Reduction Act (PRA)

The Citizens Rulemaking Alliance requested that the FAA revise the AD to comply with the PRA if reporting is required or remove any reporting provisions until PRA requirements are satisfied. If reporting is not needed, the commenter requested the FAA clarify that in the AD.

The FAA notes 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.

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.

The FAA provides the following clarification. The RFA of 1980 (5 U.S.C. 601-612), as amended by the Small Business Regulatory Enforcement Fairness Act of 1996 (Pub. L. 104-121) and the Small Business Jobs Act of 2010 (Pub. L. 111-240), 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.

This AD will affect nine domestic entities, of which four are small business entities. The table below displays the industries of the small entities, their average annual revenue, and the AD's estimated cost burden relative to average annual revenue.

While the FAA has determined that this AD affects a number of small entities, the compliance cost of the AD relative to each small entity's annual revenue is minimal. The FAA estimates the total cost per affected airplane to be $1,105 (13 work-hours × $85 per work-hour), which is less than 2% of the average small entity's annual revenue based on the number of affected airplanes in their fleet. Therefore, as provided in section 605(b), the FAA certifies this AD will not result in a significant economic impact on a substantial number of small entities. 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 De Havilland Aircraft of Canada Limited Service Bulletin 8-05-11, dated April 29, 2022. This material specifies procedures for detailed inspections for cracks and corrosion of the barrel nuts at the flight compartment windshield side posts, the nose landing gear trunnion plate assemblies, nacelle lower longeron attachments, the front, mid and rear spar horizontal stabilizer to vertical stabilizer attachments, the bathtub fittings attachments, the wing rib YW23.858 assemblies, and at the wing rib YW42.00 assemblies, and applicable corrective actions ( e.g., repairs or replacement).

The FAA also reviewed De Havilland Aircraft of Canada Limited Service Bulletin 84-27-73, dated May 8, 2019; and De Havilland Aircraft of Canada Limited Service Bulletin 8-27-121, dated July 30, 2019. This material specifies procedures, for a detailed inspection for cracks and corrosion of the barrel nuts, having part number (P/N) DSC228-4, at the rudder pedal adjustment mechanism, and applicable corrective actions ( i.e., replacement of barrel nuts, having P/N DSC228-4, with barrel nuts, having P/N B0203073-4). These documents are distinct since they apply to different airplane models.

The FAA also reviewed De Havilland Aircraft of Canada Limited Service Bulletin 8-27-122, dated July 18, 2019. This material specifies procedures for a detailed inspection for cracks and corrosion of the barrel nuts, having P/N DSC228-5, at the control attachment fittings, and applicable corrective actions ( i.e., replacement of barrel nuts, ( printed page 33586) having P/N DSC228-5, with barrel nuts, having P/N B0203073-5).

The FAA also reviewed De Havilland Aircraft of Canada Limited Service Bulletin 84-05-02, dated April 29, 2022. This material specifies procedures for detailed inspections for cracks and corrosion of the barrel nuts at the flight compartment windshield side posts, the vertical stabilizer pitch feel trim frame, the front and rear spar wing to fuselage attachment joint struts and fittings, and the bathtub fitting attachments, and applicable corrective actions ( e.g., repairs or replacement).

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.

Costs of Compliance

The FAA estimates that this AD affects 91 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any necessary on-condition actions that would be required based on the results of any required actions. The FAA has no way of determining the number of aircraft 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,

(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: