Summary
The FAA proposes to adopt a new airworthiness directive (AD) for Pratt & Whitney (PW) JT9D-3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20J turbofan engines. This proposed AD would clarify a life limit for certain part numbers of 6th stage low pressure turbine (LPT) air seals, and require their removal from service before accumulating 15,000 cycles-since-new (CSN). This proposed AD is prompted by reports of certain 6th stage LPT air seals possibly not being life tracked due to confusion from updates to the engine manuals. We are proposing this AD to prevent failure of the 6th stage LPT air seal, which could cause LPT damage resulting in an uncontained engine failure.