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

This amendment adopts a new airworthiness directive (AD), that is applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. This amendment requires a one-time inspection of low pressure turbine (LPT) 5th stage disks for evidence of blend repairs and mechanical damage, and replacement of the affected disks based on the extent of those repairs and damage. This amendment is prompted by a report of a PW JT9D-7R4G2 turbofan engine that experienced an uncontained failure of the LPT 5th stage disk. The actions specified by this AD are intended to prevent uncontained failure of the LPT 5th stage disk, due to incomplete blend repairs, resulting in in-flight shutdown and damage to the airplane.