What was found
AFTER TAKEOFF NR2 PROP BEGAN SURGING BETWEEN 1200 AND 1600 RPM. SHUTDOWN NR2 ENGINE, AND RETURNED TO FIELD. ENGINE PARAMETERS WERE NORMAL BEFORE SHUTDOWN. WE ARE WORKING WITH MFG ON THIS PROBLEM (BETA LOCK-OUT). WE HAVE ALREADY CHANGED PCU AND OVER SPEED GOVERNOR (NO FIX). AFTER MANUFACTURER REVIEWED THE FDR DOWNLOAD,IT WAS DETERMINED THAT THE AIRCRAFT PROP NEVER WENT OVER 1200RPM. AFTER TROUBLE SHOOTING THE ENGINE ELECTRICAL SYSTEM IT WAS FOUND THAT THE TORQUE SIGNIAL CONDITIONER UNIT WAS SENDING BAD INFORMATION. REPLACED TSCU,TEST FLEW THE A/C FROM SYR TO CLE. TEST FLIGHT WAS SATISFACTORY. AIRCRAFT RETURNED TO SERVICE. WILL SEND MORE INFORMATION AT LATER DATE IF NEEDED