Summary
The Federal Aviation Administration (FAA) proposes to supersede two existing airworthiness directives (ADs), applicable to Honeywell International Inc. (formerly AlliedSignal Inc. and Garrett Turbine Engine Co.) TFE731-2, -3, and -4 series turbofan engines. Those AD's currently require removing certain fan rotor discs from service in accordance with a drawdown schedule, and establishing new fan rotor disc life limits. This proposal would require stricter life limits for certain fan rotor discs. This proposal is prompted by the availability of an improved fan rotor disc and by a reduction in the probability of fan rotor disc failure by terminating the life of the older, high-stressed, fan rotor disc. The actions specified in the proposed AD are intended to prevent failure of the fan disc due to fatigue cracking in the dovetail slots, which could result in in-flight engine shutdown, uncontained engine failure, and damage to the airplane.