Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to Pratt & Whitney JT8D-200 series turbofan engines, that currently requires for front compressor front hubs (fan hubs), cleaning; initial and repetitive eddy current (ECI) and fluorescent penetrant inspections (FPI) of tierod and counterweight holes for cracks; removal of bushings; the cleaning and ECI and FPI of bushed holes for cracks; and, if necessary, replacement with serviceable parts. In addition, the current AD requires reporting the findings of cracked fan hubs. This action will not change the current AD's inspection procedures, or the effectivity date that starts the cycle count for the initial inspection schedules. This AD will, however, add an additional inspection schedule that requires the initial inspection of certain fan hubs with standard drilled holes and coolant channel drilled (CCD) holes to occur earlier than the existing AD requires. This proposal is prompted by additional investigation since publication of the current AD that reveals that certain fan hubs with standard drilled holes and CCD holes may be more susceptible to cracking. This proposal also requires reporting the results of the initial fan hub inspections. The actions specified by the proposed AD are intended to prevent fan hub failure due to tierod, counterweight, or bushed hole cracking, which could result in an uncontained engine failure and damage to the aircraft.