AD 2023-05-01

This AD is effective April 18, 2023.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of April 18, 2023.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2022-1653; 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 service information identified in this final rule, 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 in the AD docket at regulations.gov under Docket No. FAA-2022-1653.

Gabriel Kim, Aerospace Engineer, Mechanical Systems and Administrative Services Section, FAA, New York ACO Branch, 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 certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. The NPRM published in the Federal Register on December 23, 2022 (87 FR 78881). The NPRM was prompted by AD CF-2022-52, dated September 1, 2022, issued by Transport Canada, which is the aviation authority for Canada (Transport Canada AD CF-2022-52) (also referred to as the MCAI). The MCAI states there have been increasing reports of FPU pressure switch failures, part number (P/N) 150135-1 or P/N 162660-1, over the past year leading to a high number of flap inoperative events in flight and on the ground. An investigation has determined the root cause to be a deformation of the FPU pressure switch internal mechanism due to hydraulic pressure spikes. If not corrected, a failed FPU pressure switch could lead to a failure of the FPU resulting in abnormal flap landings and increased landing distances, which could require the use of emergency landing procedures and/or airfield diversions. The improved pressure switch, P/N 162660-2, has a restrictor insert in the pressure switch inlet.

In the NPRM, the FAA proposed to require replacing the FPU pressure switch or the FPU. The NPRM also proposed to prohibit the installation of affected parts. 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-2022-1653.

The FAA received no comments on the NPRM or on the determination of the cost to the public.

In the NPRM, the FAA inadvertently omitted the operational test of the wing flaps specified in Section 3.C. paragraph (2) of De Havilland Aircraft of Canada Limited Service Bulletin 84-27-75, dated June 23, 2022, including Collins Aerospace Service Bulletin 27-0029, dated June 13, 2022. The MCAI requires this step, which is important to ensure the aircraft is airworthy before it is returned to service. The FAA has therefore revised paragraphs (g)(1) and (2) of this AD to clarify that the operational test is required by this AD.

The FAA has revised paragraph (g)(2) of this AD to clarify that De Havilland Aircraft of Canada Limited Service Bulletin 84-27-75, dated June 23, 2022, including Collins Aerospace Service Bulletin 27-0029, dated June 13, 2022, is the appropriate service information for accomplishing the actions in this AD. The FAA had referred to these bulletins separately, but since they are published as one document, the FAA corrected the citation.

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 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 reviewed De Havilland Aircraft of Canada Limited Service Bulletin 84-27-75, dated June 23, 2022, including Collins Aerospace Service Bulletin 27-0029, dated June 13, 2022. This service information specifies procedures for replacing FPU P/N C148656-1 or C148656-2 with a new FPU P/N C148656-3, or replacing FPU pressure switch P/N 150135-1 or 162660-1 within the FPU with a new pressure switch P/N 162660-2 and re-identifying the FPU as P/N C148656-3, and accomplishing an operational test of the wing flaps. 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 ADDRESSES section.

The FAA estimates that this AD affects 53 airplanes 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 or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators.

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: