Action
Notice of proposed rulemaking (NPRM).
Summary
The FAA proposes to supersede Airworthiness Directive (AD) 2018-02-10, which applies to certain Pratt & Whitney Division (PW) Model PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, and PW4090-3 engines. AD 2018-02-10 requires performing repetitive fluorescent penetrant inspections (FPIs) to detect cracks in the outer diffuser case (ODC), removal of any ODC that fails inspection, and requires updating the mandatory inspections in the Airworthiness Limitations Section (ALS) of the Instructions for Continued Airworthiness (ICA). Since the FAA issued AD 2018-02-10, PW developed a modification to reduce the susceptibility of ODC cracking. This proposed AD would retain the ALS update requirement from AD 2018-02-10, would require replacing certain ODC part numbers with parts eligible for installation, would expand the applicability to all ODC part numbers, and would adjust the compliance threshold of the FPIs of the ODC. The FAA is proposing this AD to address the unsafe condition on these products.