Airworthiness Directive · Amendment 39-22524 · 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 adopting a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and - 402 airplanes. This AD was prompted by reports of the main landing gear (MLG) aft door not opening when using the alternate extension system. This AD requires a one-time inspection of the spring box assembly, repetitive inspections of the cam assembly and alternate release cable assembly, corrective actions if necessary, and a replacement of certain alternate release cable assemblies. In addition, this AD requires certain aircraft maintenance manuals tasks when installing the cam assembly or alternate release cable assembly. This AD also prohibits the installation of affected parts. The FAA is issuing this AD to address the unsafe condition on these products.
Within 2,400 flight hours or 12 months, whichever occurs first, after the effective date of this AD, do a one-time general visual inspection for discrepancies on the left and right MLG spring box assemblies (part number (P/N) 48504-1), in accordance with Section 3.B., Part A, of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-159, dated June 28, 2019. If any discrepancy is discovered in the spring box assembly, before further flight, replace with a new spring box assembly, in accordance with Section 3.B. Part B, of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-159, dated June 28, 2019.
(1) Within 2,400 flight hours or 12 months, whichever occurs first, after the effective date of this AD, do a general visual inspection for discrepancies of the cam assemblies (P/N 48510-5) on the left and right MLG, in accordance with Section 3.B. Part A, of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-159, dated June 28, 2019. Thereafter, repeat the inspection at intervals not to exceed 2,400 flight hours or 12 months, whichever occurs first. If any discrepancy is discovered in the cam assembly, before further flight, replace with a new cam assembly, in accordance with Section 3.B. Part B, of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-159, dated June 28, 2019.
(2) Within 2,400 flight hours or 12 months, whichever occurs first, after the effective date of this AD, do a general visual inspection for discrepancies of the alternate release cable assemblies (P/N 48503-3) on the left and right MLG, in accordance with Section 3.B., Part A, of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-159, dated June 28, 2019. Thereafter, repeat the inspection at intervals not to exceed 2,400 flight hours or 12 months, whichever occurs first. If any discrepancy is found, before further flight, replace the alternate release cable assembly with a redesigned alternate release cable assembly P/N 48503-5, in accordance with Section 3.B. of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-172, dated August 16, 2022, including Collins Aerospace Service Bulletin 48500-32-152, dated July 18, 2022. Accomplishing the replacement required by paragraph (i) of this AD terminates the inspections required by this paragraph.
Within 5,500 flight hours or 30 months, whichever occurs first, after the effective date of this AD, replace the left and right MLG alternate release cable assemblies, P/N 48503-3, with the redesigned alternate release cable assembly, P/N 48503-5, in accordance with Section 3.B. of the Accomplishment Instructions of De Havilland Aircraft of Canada Limited Service Bulletin 84-32-172, dated August 16, 2022, including Collins Aerospace Service Bulletin 48500-32-152, dated July 18, 2022.
As of the effective date of this AD, when installing an MLG alternate extension system cam assembly and when installing an alternate release cable assembly, the following aircraft maintenance manual (AMM) tasks must be used, as applicable:
(1) For the alternate release cable assembly: AMM TASK 32-34-16-400-804, “Installation of the Alternate Extension Cables-Center Fuselage to Nacelle” as specified in De Havilland Aircraft of Canada Limited Temporary Revision 32-603, dated December 1, 2022.
(2) For the MLG alternate extension system cam assembly: AMM TASK 32-34-26-400-801, “Installation of the MLG Alternate-Extension Cam-Mechanism Assembly” of Subject 32-34-26, “Cam Mechanism Assembly-MLG Alternative Extension” in Chapter 32, “Landing Gear,” of the De Havilland Aircraft of Canada Limited Aircraft Maintenance Manual, Revision 76, dated March 5, 2022.
