AD 2022-25-06

This AD is effective January 23, 2023.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of January 23, 2023.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2022-0993; 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 service information 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-2022-0993.

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-8-402 airplanes. The NPRM published in the Federal Register on August 12, 2022 (87 FR 49776). The NPRM was prompted by AD CF-2022-09, dated March 3, 2022, issued by Transport Canada, which is the aviation authority for Canada (referred to after this as the MCAI) (Transport Canada CF-2022-09). The MCAI states that as a result of higher-than-expected failure rates in service, the supplier's investigation found that actual operating temperatures within the IFC were significantly higher than anticipated during certification. Consequently, the reliability of the IFC module does not meet safety objectives. The MCAI further states this failure mode could lead to uncontrolled autopilot pitch trim servo runaway and/or failure of the stall warning and stick pusher, resulting in reduced controllability of the airplane.

In the NPRM, the FAA proposed to require a modification to improve the IFC cooling capacity. 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-2022-0993.

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

The FAA received an additional comment from Horizon Air. The following presents the comment received on the NPRM and the FAA's response to each comment.

Horizon Air requested that the final rule mandate only paragraph 3.B., “Procedure,” of the Accomplishment Instructions of De Havilland Service Bulletin 84-21-24, Revision B, dated Oct 13, 2021, because that corrects the unsafe condition. Horizon Air stated that paragraph 3.A. “Job Set-up,” and paragraph 3.C., “Close Out” of the Accomplishment Instructions of De Havilland Service Bulletin 84-21-24, Revision B, dated Oct 13, 2021, do not directly correct the unsafe condition. The commenter stated that incorporating the “Job Set-up” and “Close Out” procedures as a requirement of the AD restricts an operator's ability to perform other maintenance in conjunction with the incorporation of the service information.

The FAA agrees with the requested change for the reasons provided by the commenter. In addition, this change corresponds to Transport Canada AD CF-2022-09, dated March 3, 2022. The FAA has revised paragraph (g) of this AD accordingly.

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.

De Havilland Aircraft of Canada Limited has issued Service Bulletin 84-21-24, Revision B, dated October 13, 2021. This service information specifies procedures for a modification to improve the IFC cooling capacity. The tasks include reworking the forward and aft avionics rack side panels, removing the piccolo tube assemblies, doing a general visual inspection for contamination of the IFCs and avionics rack, cleaning any contamination found, installing and routing new cooling ducts, and installing two new extraction plenums in the avionics rack cooling system.

This service information 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.

The FAA estimates that this AD affects 56 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: