Summary
The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), that is applicable to Pratt & Whitney JT8D models -209, -217, -217A, -217C and -219 turbofan engines. That AD currently requires initial and repetitive fluorescent magnetic particle inspections or fluorescent penetrant inspections of the combustion chamber outer case (CCOC) for cracks, and, if necessary, replacement with serviceable parts. Also, that AD requires a one-time boss material verification, and, if necessary, replacement with serviceable parts. Finally, that AD requires replacement of CCOC's with welded-on bosses with improved, one-piece CCOC's. This proposal would require lower initial inspection thresholds for all CCOC's installed in any JT8D model -209, -217, -217A, -217C or -219 turbofan engine. This proposal is prompted by reports of cracked CCOC's that had accumulated fewer cycles in service than the initial inspection thresholds required by the current AD.Also, a CCOC part number was discovered with incorrect material not identified by serial number in PW JT8D ASB 6359. The actions specified by the proposed AD are intended to prevent uncontained failure of the CCOC, which could cause release of debris, damage to the airplane, or fire.