AD 2024-08-04

This AD is effective June 20, 2024.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2023-2137; 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, the mandatory continuing airworthiness information (MCAI), 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.

Material Incorporated by Reference:

• For De Havilland material, contact De Havilland Aircraft of Canada Limited, Dash 8 Series Customer Response Centre, 5800 Explorer Drive, Mississauga, Ontario, L4W 5K9, Canada; telephone North America (toll-free): 855-310-1013, Direct: 647-277-5820; email thd@dehavilland.com; website dehavilland.com.

• You may view this material at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available at regulations.gov under Docket No. FAA-2023-2137.

Fatin Saumik, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone: 516-228-7300; email: 9-avs-nyaco-cos@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 all De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. The NPRM published in the Federal Register on October 27, 2023 (88 FR 73775). The NPRM was prompted by AD CF-2022-59, dated October 27, 2022, issued by Transport Canada, which is the aviation authority for Canada (referred to after this as the MCAI). The MCAI states that new or more restrictive airworthiness limitations have been developed.

In the NPRM, the FAA proposed to require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. The FAA is issuing this AD to address new or more restrictive maintenance interval limitations. Failure to adhere to the specified interval limitations may result in reduced structural integrity of the airplane.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2023-2137.

The FAA received a comment from an individual who supported the NPRM without change.

The FAA received additional comments from De Havilland Aircraft of Canada Limited and Horizon Air. The following presents the comments received on the NPRM and the FAA's response to each comment.

De Havilland requested that the Costs of Compliance section of the NPRM be updated to show the correct number of affected airplanes.

The FAA agrees. The Costs of Compliance section of this AD has been updated to show 52 affected airplanes.

Horizon Air requested that the proposed AD directly mandate maintenance review board report (MRBR) tasks instead of Aircraft Maintenance Manual (AMM) tasks. Horizon noted that Transport Canada AD CF-2022-59 mandates MRBR tasks directly, and that using the AMM tasks would put an additional burden on the operator to monitor multiple sources for the same tasks. The commenter also asserted that AMM task 77-31-00-710-803, which would be required by the proposed AD, adds MRBR tasks 731100-203, 733100-201, 740000-201, 750000-201, 772100-202, and 793000-201. These tasks are not identified in Section 7-00, PSM 1-84-7—Maintenance Requirements Manual—Part 2 ALI.

The FAA does not agree because the FAA has decided to not mandate MRBRs that are part of Candidate Certification Maintenance Requirements (CCMRs), which are required by Transport Canada AD CF-2022-59. Instead of mandating the CCMR as done in the Transport Canada AD, the FAA, after coordination with Transport Canada, determined the corresponding AMM task numbers will be used. With the AMM tasks, operators must check for all engine fault codes at once, which involves reading codes from the engine fault code indicator. Although this involves more tasks, it does not add a significant number of steps. Requiring the AMM task does not pose a significant burden on the operator. This AD has not been changed with regard to this request.

Horizon Air requested that the proposed AD require only the procedure section of the AMM, with provisions for equivalent tooling and materials, rather than requiring the entire AMM maintenance task, including the job set-up, specific tools, equipment, and close-out sections. The commenter stated that mandating the entire AMM maintenance task procedure may restrict the operator's ability to perform other maintenance along with AMM tasks.

The FAA does not agree. The job set-up and close-out procedures are essential for ensuring the safety of maintenance personnel, and for ensuring the correct completion of the AMM task. This AD has not been changed with regard to this request.

Horizon Air requested clarification of whether future revisions of the AMM are allowed. Horizon noted that the proposed AD did not address whether task changes such as additions, removals, and interval adjustments could cause an operator to be out of compliance with the rule as issued.

The FAA agrees to clarify. Using the current revision of the AMMs or other revisions that incorporate the information specified in paragraph (g) of this AD is acceptable for compliance with this AD. This AD does not mandate using a specific revision of the AMM, provided that the revision used complies with the requirements of paragraph (g) of this AD.

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA reviewed the relevant data, considered the 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 this product. Except for minor editorial 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.

The FAA estimates that this AD affects 52 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA has determined that revising the maintenance or inspection program takes an average of 90 work-hours per operator, although the agency recognizes that this number may vary from operator to operator. Since operators incorporate maintenance or inspection program changes for their affected fleet(s), the FAA has determined that a per-operator estimate is more accurate than a per-airplane estimate. Therefore, the agency estimates the average total cost per operator to be $7,650 (90 work-hours × $85 per work-hour).

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: