Summary
We propose to adopt a new airworthiness directive (AD) for certain Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. This proposed AD was prompted by an in-flight failure of a 1st stage low-pressure compressor (LPC) blade. This proposed AD would require initial and repetitive thermal acoustic imaging (TAI) inspections for cracks in certain 1st stage LPC blades and removal of those blades that fail inspection. We are proposing this AD to address the unsafe condition on these products.