What was found
(CAN) A/C WAS APPROACHING AIRPORT WITH INTENTIONS TO LAND. RT ENG BETA LIGHT ON WITH OTHER ABNORMAL ENG INDICATIONS. A MISSED APPROACH INITIATED. RT ENGINE WOULD ONLY GENERATE 70 PERCENT TORQUE AND TEMPS AND FUEL FLOW WERE HIGH. PILOT IN COMMAND RETURNED TO YELLOWKNIFE AFTER CONSULTATION WITH MAINT. A/C LANDED NORMALLY. ON INVESTIGATION THE RT ENGINE WAS FOUND TO HAVE A CRACKED COMBUSTION CASE. CRACK APPEARS TO ORIGINATE AT WELD SURROUNDING FWD PLENUM DRAIN FITTING. CRACK TRAVELED A THIRD OF WAY AROUND FITTING, THEN PROGRESSED AFT FOR THREE INCHES. CRACK BRANCHED AND PORTION OF CASE FELL AWAY, CAUSING AIR LOSS THAT WAS RESPONSIBLE FOR SYMPTOMS OBSERVED ON FLIGHT DECK. ENGINE WAS REMOVED FOR REPAIR.