What was found
(CAN) DURING CLIMB, PILOT REPORTED A LOUD RUMBLE FOLLOWED BY A YAW, NR 1 ENGINE ITT WENT IN TO THE RED WITH NP AND TQ FLUCTUATING. PILOT SHUTDOWN THE NR 1 ENGINE. ACFT SAFELY RETURNED. ENGINE REMOVED AND SENT TO MFG FOR INVESTIGATION. ENGINE CHANGE COMPLETED, RUNS CARRIED OUT ACFT RTS 10713, TS LAST SHOP VISIT, 6302 CS LAST SHOP VISIT.