Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney JT9D series turbofan engines. This proposal would require 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 proposal is prompted by the finding of a crack in the web of one cooling air hole on a 1st stage HPT disk. The actions specified by the proposed AD are intended to prevent 1st stage HPT disk cracking, which could result in an uncontained engine failure and damage to the aircraft.