Airworthiness Directives; Rolls-Royce Corporation (Formerly Allison Engine Company) 250-C28 Series Engines

This amendment adopts a new airworthiness directive (AD), that is applicable to certain Rolls-Royce Corporation (formerly Allison Engine Company) 250-C28 series engines. This amendment requires removal of third stage turbine wheels, part number (P/N) 6899383, with certain serial numbers (SN's), from service before exceeding new, reduced life limits. This amendment also establishes a drawdown program to require the removal of those turbine wheels that exceed the new lower limits. This amendment is prompted by the potential to experience uncommanded shutdown caused by fractures of third stage turbine blade tips and shrouds. The actions specified by this AD are intended to prevent uncommanded shutdown of the engine due to fractures of third stage turbine blade tips and shrouds.