Federal Aviation Administration September 4, 2007 – Federal Register Recent Federal Regulation Documents

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.

The FAA is amending the certification standards for original and amended type certificates for aircraft engines by modifying the standards for engine life-limited parts. This final rule establishes new and uniform standards for the design and testing of life-limited parts for aircraft engines certificated by the FAA and the European Aviation Safety Agency (EASA). This rule retains the current lifing requirements, introduces damage tolerance requirements into the design process, and strengthens cooperation between engineering, manufacturing, and service elements of turbine engine manufacturers. These new requirements provide an added margin of safety and will reduce the number of life-limited parts failures due to material, manufacturing, and service induced anomalies. Additionally, this action adds new standards for the design of reciprocating engine turbocharger rotors.