Airworthiness Directives; Pratt & Whitney JT8D Series Turbofan Engines

This amendment supersedes an existing airworthiness directive (AD), applicable to Pratt & Whitney JT8D series turbofan engines, that currently requires inspections of low pressure turbine (LPT) blade sets for blade shroud crossnotch wear, and removal, if necessary. In addition, the current AD requires, as a terminating action to the inspections, installation of improved LPT containment hardware, and installation of an improved No. 6 bearing scavenge pump bracket bushing. This amendment keeps the compliance actions of the current AD intact but changes the compliance time for LPT containment hardware installation from the current calendar end-date to December 31, 1998, for engines that contain suspect 4th stage hubs identified by serial number. This amendment is prompted by a report of a fourth stage hub manufacturing defect that led to the failure of the hub and subsequent release of LPT blades. The actions specified by this AD are intended to prevent damage to the aircraft resulting from engine debris following an LPT blade, shaft, or hub failure.