What was found
(CAN) PILOT ON HELI-PAD, BOTH ENG ONLINE WITH TORQUE`S MATCHED. WHEN PILOT PULLED ACFT INTO HOVER NOTICED A LARGE TORQUE SPLIT BETWEEN NR 1 AND NR 2 ENG. NR 1 Q READ 60 PERCENT AND N1 ONLY READ 90.5 PERCENT. COLLECTIVE LOWERED, ACFT LANDED WITH NO PROBLEMS, PILOT RETARDED NR 2 THROTTLE TO GND. IDLE AND PULLED IN PWE ON NR 1 ENG. COULD NOT ATTAIN TORQUE 60 PERCENT N1 90.5 PERCENT. EXTENSIVE TROUBLESHOOTING OF NR 1 ENG. FUEL, AIR AND ENG CONTROLS CARRIED OUT. CHECK VALVE FROM NR 2 ENG. REMOVED AND INSTALLED ON NR 1 ENG. SUBSEQUENT ENG START ON NR 1 ENG FOUND TO BE NORMAL, WITH TORQUE RISING ABOVE 60 PERCENT AND N1 INCREASING ABOVE 90.5 PERCENT. SUSPECT CHECK VALVE REMOVED FROM SERVICE AND AVAILABLE FOR INSP.