Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney (PW) JT9D series turbofan engines. This amendment requires initial and repetitive detailed eddy current inspections for cracks in 1st stage high pressure turbine (HPT) disks, and, if necessary, replacement with serviceable parts. This amendment is prompted by the discovery of a crack in the web of one cooling air hole on a 1st stage HPT disk. The actions specified by this AD are intended to prevent 1st stage HPT disk cracking, which could result in an uncontained engine failure and damage to the aircraft.