Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Pratt & Whitney JT8D-1, -1A, -1B, -7, -7A, -7B, -9, -9A, -11, -15, - 17, and -17R series turbofan engines. This proposal would require initial and repetitive fluorescent penetrant and eddy current inspections of 4th stage low pressure turbine (LPT) hubs for cracks, and, if necessary, replacement with serviceable parts. This proposal is prompted by a report of an uncontained 4th stage LPT blade release. The actions specified by the proposed AD are intended to prevent a 4th stage LPT blade release due to hub cracking, which can result in an uncontained engine failure and damage to the aircraft.