Airworthiness Directives; Pratt & Whitney (PW) JT9D-7R4 Series Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for PW JT9D-7R4 series turbofan engines. This AD requires removing reduced cooling flow 2nd stage high pressure turbine (HPT) vane assemblies, part numbers (P/Ns) 797282, 796972, 800082, 800072, 803182, 803282, and 822582, installed in 2nd stage HPT vane cluster assemblies P/Ns 797592, 797372, 799872, 799782, and 822572. It also requires a visual and a fluorescent penetrant inspection (FPI) of the 2nd stage HPT air seal assembly, P/N 815097. This AD results from a report of an uncontained failure of the 2nd stage HPT air seal assembly, caused by the air seal assembly brace disengaging from the air seal, due to insufficient cooling air flow. We are issuing this AD to prevent uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane.