Airworthiness Directives; Bombardier Model DHC-8-400, -401, and -402 Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Bombardier Model DHC-8-400, -401, and -402 airplanes. This AD requires an inspection to determine the serial number of the spoiler lift dump valves installed on the inboard and outboard spoilers, and replacement of certain spoiler lift dump valves. This AD also provides for revising the airplane flight manual to include performance penalties, which allows the replacement of affected spoiler lift dump valves to be deferred. This action is necessary to prevent failure of the ground spoilers to deploy on the ground, which could result in overrunning the end of the runway in the event of a rejected takeoff. This action is intended to address the identified unsafe condition.