Summary
This document proposes to revise an existing airworthiness directive (AD), applicable to Pratt & Whitney JT9D series turbofan engines, that currently requires initial and repetitive eddy current inspections (ECI) of 14th and 15th stage high pressure compressor (HPC) disks for cracks, and removal of cracked disks and replacement with serviceable parts. This action would revise the definition of a shop visit to make compliance less restrictive, and add references to a Nondestructive Inspection Procedure attached to applicable service bulletins. This proposal is prompted by feedback from operators saying that the shop visit definition in the current AD made AD compliance unnecessarily restrictive. The actions specified by the proposed AD are intended to prevent 14th and 15th stage HPC disk rupture, which could result in an uncontained engine failure and damage to the aircraft.