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

요약

The FAA proposes to supersede an existing airworthiness directive (AD) for PW JT9D-7R4 series turbofan engines. That AD currently requires removing certain reduced cooling flow 2nd stage high pressure turbine (HPT) vane assemblies installed in certain 2nd stage HPT vane cluster assemblies. It also requires a visual and a fluorescent penetrant inspection (FPI) of the 2nd stage HPT air seal assembly, P/N 815097. This proposed AD would require a visual and fluorescent penetrant inspection (FPI) of all part number (P/N) 2nd stage HPT air seal assemblies that were used with reduced cooling flow 2nd stage HPT vane assemblies. This proposed AD results from the manufacturer identifying additional P/N air seal assemblies that are affected by the unsafe condition. We are proposing 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.