Airworthiness Directives; Pratt & Whitney Canada PW206A and PW206E Turboshaft Engines

The FAA is superseding an existing airworthiness directive (AD) for Pratt & Whitney Canada (PWC) PW206A and PW206E turboshaft engines. That AD currently requires: <bullet> Initial and repetitive borescope inspections of compressor turbine and power turbine blades for blade axial shift. <bullet> Replacement of blade retaining rivets and certain rotor air seals as terminating action for the repetitive borescope inspections. This ad requires the same actions as AD 2003-NE-25-AD but the extent of engine disassembly that triggers the required part replacements needs clarification. This AD results from reports of engine shutdowns and emergency landings due to severe vibration, resulting in exhaust gases escaping from the engine-to-exhaust nozzle interface, thereby triggering in-flight engine fire warnings. We are issuing this AD to prevent turbine blade axial shift, which could cause high levels of vibration, loss of engine torque, in-flight engine shutdown, and loss of the airframe exhaust duct.