Airworthiness Directive · Amendment 39-22769 · Landing gear
De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes
This AD applies to De Havilland Aircraft of Canada Limited (Type Certificate previously held by Bombardier, Inc.) Model DHC-8-401 and -402 airplanes, certificated in any category, having serial numbers 4001, and 4003 through 4633 inclusive.
The FAA is superseding Airworthiness Directive (AD) 2021-25-12 and AD 2022-11-11, which applied to certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. AD 2021-25-12 required repetitive lubrications of the trailing arm of the nose landing gear (NLG). AD 2021-25-12 also required revising the existing maintenance or inspection program to include new and revised airworthiness limitations. AD 2022-11-11 required a modification to the NLG shock strut assembly. This AD continues to require the actions specified in AD 2021-25-12 and AD 2022-11-11 and requires replacement of the pivot pin and tow fitting assembly with a new, improved pivot pin and tow fitting assembly and prohibits the installation of affected parts. This AD was prompted by a determination that the pivot pin and tow fitting assembly of the NLG must be replaced. The FAA is issuing this AD to address the unsafe condition on these products.
This paragraph restates the requirements of paragraph (g) of AD 2021-25-12, with no changes. For airplanes with pivot pin retention bolt part number (P/N) NAS6204-14D installed on the NLG assembly: Within 30 days after January 5, 2022 (the effective date of AD 2021-25-12), or within 30 days after installation of pivot pin retention bolt part number P/N NAS6204-14D, whichever occurs later, revise the existing maintenance or inspection program, as applicable, to incorporate the information for Structures Safe Life Task 32-21-01-701 and Task 32-21-01-702, as specified in De Havilland Aircraft of Canada Limited Temporary Revision ALI-0223, dated October 15, 2020. The initial compliance time for doing the tasks is at the applicable time specified in De Havilland Aircraft of Canada Limited Temporary Revision ALI-0223, dated October 15, 2020, or within 30 days after January 5, 2022, whichever occurs later; except, if replacement of bolt P/N NAS6204-14D was performed before January 5, 2022, as specified in De Havilland Aircraft of Canada Service Bulletin 84-32-161, the initial compliance time for Task 32-21-01-702 (bolt P/N NAS6204-14D replacement) is within 3 months after January 5, 2022, or within 800 flight cycles after performing the replacement, whichever occurs later.
This paragraph restates the requirements of paragraph (h) of AD 2021-25-12, with no changes. After the existing maintenance or inspection program has been revised as required by paragraph (g) of this AD, no alternative actions (e.g., replacements) or intervals may be used unless the actions and intervals are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (n)(1) of this AD.
This paragraph restates the requirements of paragraph (i) of AD 2021-25-12, with no changes. For airplanes with pivot pin retention bolt P/N NAS6204-14D installed on the NLG assembly: Within 30 days or 400 flight cycles, whichever occurs first after January 5, 2022 (the effective date of AD 2021-25-12), and thereafter at intervals not exceeding 400 flight cycles, lubricate the trailing arm of the NLG, including doing a general visual inspection of the NLG pivot pin mechanism for discrepancies (i.e., bolt P/N NAS602-14D is missing or has damage (e.g., stress corrosion or stress corrosion cracking)) and, as applicable, replacing the bolt before further flight, in accordance with paragraph 3.B. of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-167, dated August 12, 2021.
This paragraph restates the requirements of paragraph (g) of AD 2022-11-11, with no changes. For any airplane having an NLG shock strut assembly, P/N 47100-XX (where XX represents any number), that has special bolt P/N 47205-1 or 47205-3: Within 1,600 flight cycles or 9 months after July 8, 2022 (the effective date of AD 2022-11-11), whichever occurs first, modify the NLG shock strut assembly, in accordance with paragraph 3.B., “Procedure,” of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-161, Revision B, dated March 31, 2021, including UTC Aerospace Systems Service Bulletin 47100-32-145, Revision 3, dated March 26, 2021.
Note 1 to paragraph (j): After installing pivot pin retention bolt part number NAS6204-14D, paragraphs (g), (h), and (i) of this AD apply to pivot pin retention bolt part number NAS6204-14D.
Within 8,000 flight hours or 48 months, whichever occurs first, after the effective date of this AD, remove pivot pin linkage components and replace pivot pin P/N 47127-1 or P/N 47127-3 and tow fitting assembly P/N 47160-1 with pivot pin P/N 47127-5 and tow fitting assembly P/N 47160-3, in accordance with Section 3.B. of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-173, dated November 15, 2022, including Collins Aerospace Service Bulletin 47100-32-153, dated November 10, 2022. Accomplishing the replacement required by this paragraph terminates the requirements of paragraphs (g), (h), (i), and (j) of this AD.
