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Action

Notice of proposed rulemaking (NPRM).

Summary

We propose to adopt a new airworthiness directive (AD) for certain Pratt & Whitney Division PW4000-94" and PW4000-100" turbofan engines having a 1st stage high-pressure turbine (HPT) seal support, part number (P/N) 55K601 or P/N 50K532, installed. This proposed AD was prompted by 58 reports of cracked 1st stage HPT air seal rings, including 15 in-flight engine shutdowns. This proposed AD would require installation of a redesigned 1st stage HPT seal support that was introduced to the PW4000 engine fleet through service bulletins issued in the year 2000. We are proposing this AD to prevent failure of the 1st stage HPT air seal ring, which could lead to an internal oil fire, uncontained engine failure, and damage to the airplane.

Document

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