Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Aerospatiale Model ATR42-200, -300, -320, and -500 series airplanes and all Model ATR72 series airplanes. This proposal would require 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 proposal would also require replacement of defective engine fire handles with serviceable fire handles, which would terminate the revision of the AFM and the repetitive tests of the engine fire protection system. This action is necessary to prevent improper functioning of the engine fire handles, due to a machining defect of the control shaft bore guide, which could result in failure of the engine fire extinguisher to operate properly. This action is intended to address the identified unsafe condition.