Airworthiness Directives; Aerospatiale Model ATR42-200, -300, -320, and -500 Series Airplanes, and Model ATR72 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model ATR42-200, -300, -320, and - 500 series airplanes and Model ATR72 series airplanes, that requires temporarily revising the Airplane Flight Manual (AFM) to add tests of the engine fire protection system and conducting those tests prior to each flight. This amendment also requires replacement of defective engine fire handles with serviceable fire handles, which terminates the revision of the AFM and the repetitive tests of the engine fire protection system. These actions are necessary to prevent intermittent improper functioning of the engine fire handles, due to a machining defect of the control shaft bore guide, which could result in malfunction of the trigger (squib), and failure to activate one of the two engine fire extinguishers. This action is intended to address the identified unsafe condition.