As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) FOLLOWING TAKE-OFF, THE ENGINE EXPERIENCED AN UNCOMMANDED TORQUE REDUCTION ACCOMPANIED BY A REDUCTION IN PROPELLER SPEED. THE ENGINE WAS SHUT DOWN IN FLIGHT AND THE AIRCRAFT DIVERTED TO POINT OF DEPARTURE. SUBSEQUENT INSPECTION REVEALED AN UNSERVICEABLE TORQUE SIGNAL CONTROL UNIT (TSCU).