Airworthiness Directive · Amendment 39-12685 · Rolls-Royce Corporation (Formerly Allison Engine Company) 250-C28 Series Engines
Rolls-Royce Corporation (Formerly Allison Engine Company) 250-C28 Series Engines
This airworthiness directive (AD) is applicable to Rolls-Royce Corporation (formerly Allison Engine Company) 250- C28, -C28B, and -C28C model engines with third stage turbine wheels part number (P/N) 6899383, listed by serial number (SN) in the following Table 1: Table 1.--SN's of Affected Third Stage Turbine Wheels HX91428R HX91489R HX91707R HX91456R HX91490R HX91708R HX91457R HX91492R HX91709R HX91458R HX91493R HX91710R HX91459R HX91494R HX91711R HX91461R HX91500R HX91712R HX91462R HX91501R HX91713R HX91464R HX91503R HX91714R HX914659 HX91504R HX91715R HX91465R HX91506R HX91721R HX91466R HX91507R HX91722R HX91467R HX91508R HX91726R HX91468R HX91510R HX91733R HX91469R HX91511R HX91735R HX91471R HX91512R HX91736R HX91472R HX91513R HX91738R HX91473R HX91519R HX91742R HX91474R HX91520R HX91744R HX91475R HX91522R HX91748R HX91477R HX91523R HX91749R HX91478R HX91524R HX91750R HX91480R HX91525R HX91754R HX91482R HX91526R HX91764R HX91483R HX91527R HX91765R HX91485R HX91528R HX91766R HX91486R HX91529R HX91767R HX91487R HX91530R HX91768R HX91488R HX91706R HX91769R Note.--These engines are installed on, but not limited to Bell Helicopter Textron 206L-1 helicopters.
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.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
