Airworthiness Directives; De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes

DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 39</CFR> <DEPDOC>[Docket No. FAA-2025-2558; Project Identifier MCAI-2021-00022-T]</DEPDOC> <RIN>RIN 2120-AA64</RIN> <SUBJECT>Airworthiness Directives; De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Notice of proposed rulemaking (NPRM). <SUM> <HD SOURCE="HED">SUMMARY:</HD> The FAA proposes to adopt a new airworthiness directive (AD) for all De Havilland Aircraft of Canada Limited Model DHC-8 airplanes. This proposed AD was prompted by reports of cracked barrel nuts at the wing front spar and horizontal stabilizer to vertical stabilizer joint. This proposed AD would require repetitive inspections for cracking and corrosion of the affected barrel nuts and applicable corrective actions. The FAA is proposing this AD to address the unsafe condition on these products. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> The FAA must receive comments on this proposed AD by November 13, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: • <E T="03">Federal eRulemaking Portal:</E> Go to <E T="03">regulations.gov</E> . Follow the instructions for submitting comments. • <E T="03">Fax:</E> 202-493-2251. • <E T="03">Mail:</E> U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. • <E T="03">Hand Delivery:</E> Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. <E T="03">AD Docket:</E> You may examine the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-2558; 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 NPRM, the mandatory continuing airworthiness information (MCAI), any comments received, and other information. The street address for Docket Operations is listed above. Material Incorporated by Reference • For De Havilland Aircraft of Canada Limited material identified in this proposed AD, 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 <E T="03">thd@dehavilland.com</E> ; website <E T="03">dehavilland.com</E> . • 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. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7300; email: <E T="03">9-avs-nyaco-cos@faa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Comments Invited</HD> The FAA invites you to send any written relevant data, views, or arguments about this proposal. Send your comments using a method listed under the <E T="02">ADDRESSES</E> section. Include “Docket No. FAA-2025-2558; Project Identifier MCAI-2021-00022-T” at the beginning of your comments. The most helpful comments reference a specific portion of the proposal, explain the reason for any recommended change, and include supporting data. The FAA will consider all comments received by the closing date and may amend the proposal because of those comments. Except for Confidential Business Information (CBI) as described in the following paragraph, and other information as described in 14 CFR 11.35, the FAA will post all comments received, without change, to <E T="03">regulations.gov</E> , including any personal information you provide. The agency will also post a report summarizing each substantive verbal contact received about this NPRM. <HD SOURCE="HD1">Confidential Business Information</HD> CBI is commercial or financial information that is both customarily and actually treated as private by its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public disclosure. If your comments responsive to this NPRM contain commercial or financial information that is customarily treated as private, that you actually treat as private, and that is relevant or responsive to this NPRM, it is important that you clearly designate the submitted comments as CBI. Please mark each page of your submission containing CBI as “PROPIN.” The FAA will treat such marked submissions as confidential under the FOIA, and they will not be placed in the public docket of this NPRM. Submissions containing CBI should be sent to Christopher Spencer, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; phone: (516) 228-7300; email: <E T="03">9-avs-nyaco-cos@faa.gov</E> . Any commentary that the FAA receives which is not specifically designated as CBI will be placed in the public docket for this rulemaking. <HD SOURCE="HD1">Background</HD> Transport Canada, which is the aviation authority for Canada, has issued Transport Canada AD CF-2020-06R1, dated January 7, 2021 (Transport Canada AD CF-2020-06R1) (also referred to as the MCAI), to correct an unsafe condition for all De Havilland Aircraft of Canada Limited Model DHC-8-100 series airplanes; Model DHC-8-200 series airplanes; Model DHC-8-300 series airplanes (which includes Model DHC-8-314 airplanes); and Model DHC-8-400 series airplanes. Model DHC-8-314 airplanes are not certificated by the FAA and are not included on the U.S. type certificate data sheet; this proposed AD therefore does not include those airplanes in the applicability. 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 AD CF-2011-24R1 (which corresponds to FAA AD 2019-20-09, Amendment 39-19762 (84 FR 56680, October 23, 2019)) and 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 ( <E T="03">i.e.,</E> of the airplane) and could lead to loss of control of the airplane. The FAA is proposing this AD to address the unsafe condition on these products. You may examine the MCAI in the AD docket at <E T="03">regulations.gov</E> under Docket No. FAA-2025-2558. <HD SOURCE="HD1">Material Incorporated by Reference Under 1 CFR Part 51</HD> 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 T="03">e.g.,</E> 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 ( <E T="03">i.e.,</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 ( <E T="03">i.e.,</E> replacement of barrel nuts, 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 T="03">e.g.,</E> 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 <E T="02">ADDRESSES</E> section. <HD SOURCE="HD1">FAA's Determination</HD> 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 and material referenced above ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 25k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━