Airworthiness Directive · Amendment 39-22370 · Flight controls
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, 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-8-400 series airplanes. This AD was prompted by reports of flap power unit (FPU) pressure switch failures resulting in flap inoperative events. This AD requires replacing the FPU or replacing the FPU pressure switch and reidentifying the FPU. This AD also prohibits the installation of affected parts. The FAA is issuing this AD to address the unsafe condition on these products.
Within 8,000 flight hours or 48 months after the effective date of this AD, whichever occurs first: Do the actions specified in either paragraph (g)(1) or (2) of this AD.
(1) Replace FPU part number (P/N) C148656-1 or C148656-2 with P/N C148656-3 and do an operational test of the wing flaps in accordance with Section 3.B. paragraph (1) and Section 3.C. paragraph (2), of the Accomplishment Instructions 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.
(2) Replace FPU pressure switch P/N 150135-1 or 162660-1 with P/N 162660-2, reidentify the FPU as P/N C148656-3, and do an operational test of the wing flaps in accordance with Section 3.B. paragraph (2) and Section 3.C. paragraph (2), of the Accomplishment Instructions 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.
