Airworthiness Directives; Bombardier Model DHC-8-100, -200, and -300 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes. This action requires a one-time visual inspection to determine the part numbers of the beta back-up test switches of the propeller control system, and replacement of the switches, if necessary. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified in this AD are intended to prevent loss of the automatic overspeed protection of the propeller control system, which could result in a propeller overspeed condition and possible damage to the engine and propeller.