Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all Pratt & Whitney Division (Pratt & Whitney) PW4052, PW4056, PW4060, PW4062, PW4062A, PW4074, PW4077, PW4077D, PW4084D, PW4090, PW4090-3, PW4152, PW4156A, PW4158, PW4164, PW4168, PW4168A, PW4460, and PW4462 turbofan engines. The existing AD currently requires initial and repetitive fluorescent penetrant inspections (FPI) for cracks in the blade locking and loading slots of the high-pressure compressor (HPC) drum rotor disk assembly rear drum. Since we issued that AD, Pratt & Whitney has developed a redesigned HPC drum rotor disk assembly for certain affected engine models. This proposed AD would also require replacement of the 13th, 14th, and 15th stage HPC seals as an additional action and would add an optional terminating action to the repetitive inspection requirements by allowing replacement of the entire HPC drum rotor disk assembly. We are proposing this AD to prevent failure of the HPC drum rotor disk assembly, which could lead to an uncontained engine failure, and damage to the airplane.