Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines

This amendment supersedes an existing airworthiness directive (AD), that is applicable to certain Pratt & Whitney JT9D series turbofan engines. That AD currently requires revisions to the Airworthiness Limitations Section (ALS) of the manufacturer's Instructions for Continued Airworthiness (ICA) to include required enhanced inspection of selected critical life-limited parts at each piece-part exposure. This action adds additional critical life-limited parts for enhanced inspection. This amendment is prompted by an FAA study of in-service events involving uncontained failures of critical rotating engine parts. The actions specified by this AD are intended to prevent critical life-limited rotating engine part failure, which could result in an uncontained engine failure and damage to the airplane.