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

This amendment adopts a new airworthiness directive (AD) that applies to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. This amendment requires on JT9D-7R4 series turbofan engines with steel fan cases, replacement of the existing one-piece fan case shield with a thicker four-piece fan case shield and would add four fan case shield supports. This amendment results from two uncontained full fan blade fracture events that resulted in penetration of the steel fan case and fan case shield. We are issuing this AD to prevent uncontained fan blade failures, resulting in damage to the airplane.