Airworthiness Directives; Pratt & Whitney (PW) Models PW4074 and PW4077 Turbofan Engines

Résumé

The FAA proposes to adopt a new airworthiness directive (AD) for PW PW4074 and PW4077 turbofan engines with 15th stage high-pressure compressor (HPC) disks, part number (P/N) 55H615, installed. This proposed AD would require removing the 15th stage HPC disk within 12,000 cycles since new (CSN) or, for any disks that exceed 12,000 CSN after the effective date of this AD using a drawdown plan that includes a borescope inspection (BSI) or eddy current inspection (ECI) of the rim for cracks. This proposed AD results from multiple shop findings of cracked 15th stage HPC disks. We are proposing this AD to prevent cracks from propagating into the bolt hole, which could result in a failure of the 15th stage HPC disk, uncontained engine failure, and damage to the airplane.