Airworthiness Directives; Honeywell International Inc. TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, -5R, -20R, -20AR, -20BR, -40, -40AR, -40R, and -60 Series Turbofan Engines

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The FAA proposes to adopt a new airworthiness directive (AD) for Honeywell International Inc. (Honeywell) TFE731-2C, -3B, -3BR, -3C, -3CR, -3D, -3DR, -4R, -5AR, -5BR, -5R, -20R, -20AR, -20BR, -40, -40AR, -40R, and -60 series turbofan engines. This proposed AD would require removal from service of certain high pressure (HP) turbine rotor assemblies with part numbers (P/Ns) 3075772-1 and 3060841-1 using a drawdown schedule, and returning them to Honeywell for curvic root radius inspection. This proposed AD results from the manufacturer's report that some HP turbine rotor discs received improperly machined radii in the root of the forward and aft curvic teeth during manufacture. We are proposing this AD to prevent uncontained failure of the HP turbine rotor assembly and damage to the airplane.