Airworthiness Directive · Amendment 39-18275 · Flight controls
Bombardier, Inc. Airplanes
This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category, serial numbers 4001 and 4003 through 4453 inclusive with an outboard spoiler power control unit (PCU) having part number 390700-1007 installed in the outboard position.
We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted by reports of inadvertent deployment of a single outboard spoiler during flight. This AD requires replacement of the power control units (PCUs) for the outboard spoilers with upgraded PCUs. We are issuing this AD to prevent leakage of the piston head seal and piston rod seals of the outboard spoiler PCUs, which could result in inadvertent spoiler deployment and reduced controllability of the airplane.
Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first: Replace the outboard spoiler PCUs with upgraded PCUs having re-designed seals, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-27-63, dated October 17, 2013.
