Airworthiness Directives; Boeing Model 737-700 and -800 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-700 and -800 series airplanes. This action requires a one-time inspection to determine the serial numbers of the fire detector assemblies and elements for the auxiliary power unit (APU) and engines, and replacement of the assemblies or elements with new or serviceable parts, if necessary. This amendment is prompted by a report indicating that certain fire detector elements were not checked for leaks during manufacturing and, therefore, may not have the correct set points for the fire warning system. The actions specified in this AD are intended to prevent failure of the APU or engine fire detection systems to detect a fire in a timely manner, which could result in egress of an APU or engine compartment fire to other parts of the airplane.