What was found
(CAN) AUTOFEATHER/IFSD WHILE IN CLIMB THROUGH FL160, SEVERE TORQUE FLUCTUATIONS OCCURRED FOLLOWED BY THE PROPELLER GOING TO FEATHER. THE FIRE WARNING WAS ACTIVATED AND THE CREW APPLIED THE COMPLETE FIRE DRILL AND SHUT THE ENGINE DOWN. AN UNEVENTFUL SINGLE ENGINE LANDING FOLLOWED AT THE POINT OF DEPARTURE. POST FLIGHT INSPECTION FOUND NO EVIDENCE OF FIRE DAMAGE HOWEVER, THE 2ND STAGE POWER TURBINE BLADES AND STATOR SHOWED SEVERE HEAT DISTRESS.