Airworthiness Directive · Amendment 39-13211 · Pratt & Whitney PW4074, PW4074D, PW4077, PW4077D, PW4090, and PW4090-3 Turbofan Engines
Pratt & Whitney PW4074, PW4074D, PW4077, PW4077D, PW4090, and PW4090-3 Turbofan Engines
This AD is applicable to Pratt & Whitney (PW) PW4074, PW4074D, PW4077, PW4077D, PW4090, and PW4090-3 turbofan engines with high pressure compressor (HPC) rear cases, part numbers (P/Ns) 55H425-01, 55H385-01, and 56H396-01 installed. These engines are installed on, but not limited to, Boeing 777 series airplanes.
The FAA is adopting a new airworthiness directive (AD) for Pratt & Whitney (PW) PW4074, PW4074D, PW4077, PW4077D, PW4090, and PW4090-3 turbofan engines with high pressure compressor (HPC) rear cases, part numbers (P/Ns) 55H425-01, 55H385-01, and 56H396-01 installed. This AD requires initial and repetitive visual or fluorescent penetrant inspections (FPI) of the J flange on the HPC rear case, and removal from service of the rear case based on certain inspection results. This AD is prompted by reports of cracks propagating from bolt holes in the HPC rear case J flange, and reports of high-cycle HPC rear cases exhibiting cracks propagating into the shell wall. The actions specified in this AD are intended to prevent fracturing and rupturing of the HPC rear case, resulting in uncontained engine failure.
