Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to adopt a new airworthiness directive (AD) for certain PW4000 turbofan engines. This proposed AD was prompted by an updated low-cycle fatigue (LCF) life analysis performed by Pratt & Whitney. This proposed AD would require removing certain part number (P/N) high-pressure turbine (HPT) stage 1 and HPT stage 2 airseals and HPT stage 1 airseal rings before their published life limit, and establishes a new lower life limit for these parts. We are proposing this AD to correct the unsafe condition on these products.