Summary
We propose to adopt a new airworthiness directive (AD) for Pratt & Whitney JT9D-7R4D, -7R4D1, -7R4E, -7R4E1, -7R4G2, -7R4H1, and - 7R4E4 turbofan engines. This proposed AD would establish a new lower life limit for high-pressure turbine (HPT) 1st stage air seals, part number (P/N) 735907, and would require removing them from service using a drawdown schedule. This proposed AD was prompted by the determination that a new lower life limit for the HPT 1st stage air seals, P/N 735907, is necessary. We are proposing this AD to prevent critical life-limited rotating engine part failure and damage to the airplane.