Airworthiness Directive · Amendment 39-21566 · 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-8-400, -401, and -402 airplanes, certificated in any category, having serial numbers 4001, and 4003 through 4534 inclusive.
The FAA is adopting a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-400, -401, and -402 airplanes. This AD was prompted by a report of main landing gear (MLG) retractions after striking an obstacle or severe wheel imbalance after a tire failure. This AD requires inspections for correct height of the lock link over-center stop pin and for correct gaps of the left-hand and right-hand MLG downlock proximity sensors, replacement of the shim if necessary, corrective actions, and installation of a new, improved proximity sensor electronic unit (PSEU) with software changes. The FAA is issuing this AD to address the unsafe condition on these products.
Within 9 months after the effective date of this AD: Verify both the height of the lock link over-center stop pin and the gap of the left-hand and right-hand MLG downlock proximity sensors, and perform corrective actions as required, in accordance with paragraphs 3.A. and 3.B. of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-140, Revision B, dated January 30, 2018. Do all applicable corrective actions before further flight.
Within 18 months after the effective date of this AD, install PSEU P/N 30145-0601 in accordance with paragraphs 3.A. and 3.B. of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-143, Revision B, dated November 16, 2016.
Installing PSEU P/N 30145-0602 in accordance with paragraphs 3.A. and 3.B. of the Accomplishment Instructions of Bombardier Service Bulletin 84-32-149, dated November 16, 2016, also accomplishes the requirements of paragraphs (g) and (h) of this AD.
