Airworthiness Directives; Aerospatiale Model ATR 42-300 and 42- 320 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Aerospatiale Model ATR42-300 and -320 series airplanes. This action requires modification of the electrical wire bundle associated with the smoke detection system. This amendment is prompted by a report of a short circuit in this electrical wire bundle, which was caused by chafing of the wire against a smoke detection pipe. The actions specified in this AD are intended to prevent such chafing, which could result in short circuits of the electrical wire bundle and a potential fire hazard.