Airworthiness Directives; Rolls-Royce Corporation Turboshaft Engines

We are superseding Airworthiness Directive (AD) 2015-02-22 for certain Rolls-Royce Corporation (RRC) model 250 turboprop and turboshaft engines. AD 2015-02-22 required repetitive visual inspections and fluorescent-penetrant inspection (FPIs) on certain 3rd- stage and 4th-stage turbine wheels for cracks in the turbine wheel blades. This AD requires repetitive visual inspections and FPIs of 3rd- stage turbine wheels while removing from service 4th-stage turbine wheels. We are also revising the applicability to remove all RRC turboprop engines and add additional turboshaft engines. This AD was prompted by our finding that it is necessary to remove the 4th-stage wheels at the next inspection. We are issuing this AD to address the unsafe condition on these products.