As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING ROUTINE SURVEILLANCE MISSION, CREW REPORTED LOUD NOISE FOLLOWED BY A ROLL BACK IN TORQUE TO ZERO & CORRESPONDING YAW. THE HIGH PRESS NH & LOW PRESS NL COMPRESSOR ROTOR SPEED MAINTAINED ROTATION. THE CREW FEATHERED PROPELLER & COMPLETED SHUTDOWN PROCEDURE. THE ACFT LANDED UNEVENTFULLY.