What was found
(CAN) DURING CLIMB, PASSING FL180, THE CREW OBSERVED THE ENGINE TORQUE INDICATING ZERO. THEY IMMEDIATELY REDUCED THROTTLE AND THEN THE CONDITION LEVER, ACTUALLY SHUTTING DOWN THE ENGINE, NO MASTER CAUTION WARNING OCCURRED. THE CREW DECIDED TO RETURN TO THE DEPARTURE POINT WHERE AN UNEVENTFUL SINGLE ENGINE LANDING WAS MADE. TROUBLESHOOTING IS FOCUSING ON A POSSIBLE UNCOMMANDED AUTOFEATHER ISSUE. P&WC WILL INVESTIGATE TO ESTABLISH ROOT CAUSE AND SUPPLEMENT THE REPORT ONCE THE INFORMATION IS AVAILABLE.