Summary
This notice revises an earlier proposed airworthiness directive (AD), applicable to Pratt & Whitney (PW) JT8D series turbofan engines, that would have superseded a current AD by reducing the rear flange inspection interval for combustion chamber outer cases (CCOC's) when only the aft face of the rear flange has been inspected, and introducing an improved ultrasonic probe assembly. That proposal was prompted by reports of crack origins in the forward face of the rear flange that could not be detected by the inspection methods for installed CCOC's that were mandated in the current AD. This action retains the elements of the original proposal, but simplifies the compliance instructions, and incorporates a new PW Alert Service Bulletin (ASB). This action also revises the proposed rule by introducing new non-destructive inspection procedures (NDIP's), and introducing a rotating eddy current probe for shop inspections in which the case is removed from the engine. In addition, this action eliminates fluorescent penetrant inspection (FPI), fluorescent magnetic particle inspection (FMPI), and visual inspections from hot section disassembly level inspection procedures. This action also revises the proposed rule by consolidating the inspection requirements of an additional current AD, 95-08-15, into this proposed AD. The actions specified by this proposed AD are intended to prevent CCOC flange cracks that could result in uncontained engine failure, inflight engine shutdown, engine cowl release, and airframe damage.