Airworthiness Directives; Pratt & Whitney Division

We propose to adopt a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 turbofan engines. This proposed AD was prompted by the discovery of multiple cracked outer diffuser cases. This proposed AD would require initial and repetitive inspections to detect cracks in the outer diffuser case and removal from service of cases that fail inspection. We are proposing this AD to address the unsafe condition on these products.