Summary
The FAA proposes to adopt a new airworthiness directive (AD) for Pratt & Whitney PW4074, PW4074D, PW4077, PW4077D, PW4084D, PW4090, PW4090-3, and PW4098 turbofan engines, with certain front turbine hub part numbers installed. This proposed AD would require a onetime visual inspection of the anti-rotation slots in the front turbine hub, for a machining nonconformance, and its replacement if the inspection failed. This proposed AD results from a report of a crack found in an anti- rotation slot of a front turbine hub, during overhaul shop inspection. The anti-rotation slot geometry was not machined in conformance with the design drawing. We are proposing this AD to prevent uncontained engine failure, damage to the airplane, and injury to passengers.