Summary
The FAA proposes to adopt a new airworthiness directive (AD) for Pratt & Whitney Canada (PWC) models PW118, PW120, PW120A, and PW121 turboprop engines. This proposed AD would require replacing the low pressure rotor speed (NL) sensor port sealing tube and reworking or replacing the external air tube connecting the P2.5/P3 switching valve to the rear inlet case. This proposed AD is prompted by a report of an internal oil fire in the engine intercompressor case (ICC). A fire in the ICC could cause the existing tubes to disengage due to melted brazing on the tubes. Once these tubes disengage, the ICC fire then develops into an external fire within the engine nacelle cavity. The actions specified in this proposed AD are intended to prevent fire in the engine nacelle cavity, in-flight engine shutdown, and airplane damage.