Summary
We propose to adopt a new airworthiness directive (AD) for Pratt & Whitney PW4052, PW4152, PW4056, PW4156A, PW4060, PW4060A, PW4060C, PW4062, PW4062A, PW4158, PW4460, PW4462, PW4164, PW4164C, PW4164C/B, PW4168, and PW4168A turbofan engines with certain high- pressure turbine (HPT) stage 1 front hubs installed. This proposed AD was prompted by Pratt & Whitney's updated low-cycle-fatigue analysis that indicated certain HPT stage 1 front hubs could initiate a crack prior to the published life limit. This proposed AD would require removing the affected HPT stage 1 front hubs from service using a drawdown plan. We are proposing this AD to prevent failure of the HPT stage 1 front hub, which could lead to an uncontained engine failure and damage to the airplane.