What was found
ACFT DEPARTED. 7 MINUTES INTO FLIGHT, 1600 FT MSL, CLIMBING TO 2000 FT, FADEC FAULT CAUTION ILLUMINATED. BETWEEN 10 & 15 SECONDS LATER ACFT EXPERIENCED A VIOLENT LEFT YAW OF APPROX 45 DEGREES. AN AUTOROTATIVE DESCENT IMMEDIATELY INITIATED. DURING DESCENT, NR NOTED AT 100 PERCENT & NP AT 80-85 PERCENT. EMERGENCY PROCEDURE FOR ENGINE UNDERSPEED COMPLETED, FADEC PLACED IN MANUAL MODE, NR & NP MATCHED. FLT STABILIZED AT APPROX 400 FT AGL, NO FLUCTUATIONS INDICATED. RETUREND TO BASE. ON FINAL & REDUCTION OF POWER TO INITIATE APPROACH, DISCOVERED THE THROTTLE DID NOT RESPOND APPROPRIATELY. IT TOOK A SIGNIFICANTLY LARGE AMOUNT OF THROTTLE INPUT TO AFFECT THE NP. ACFT LANDED WITHOUT FURTHER INCIDENT.