PC-12
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 75; Flight Crew Total 5000; Flight Crew Type 700
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport
Aircraft
[We] lined up for takeoff. After setting power at 43 PSI Torque; a standard takeoff occurred. At approximately 300 ft. AGL; the Master Caution illuminated and I saw the Torque gauge surging back and forth from 35-51 PSI (above max limitations); without anyone touching the throttle. I tried adjusting the throttle lower; to no avail. I did not feel the engine itself surge; but being so close to the ground and concentrating on flying; I could not check all the other gauges and diagnose the problem properly. I asked the copilot (who had just switched to departure frequency) to advise we needed to remain in the pattern and return to land immediately. The copilot relayed that to ATC; who asked if we were [requesting] for priority (they were busy at the time). We remained left closed traffic and ran the appropriate check lists. Once the power was pulled back to about 30 PSI; the torque surging stopped. Two aircraft on final were given go around/vectors as a result of our [situation]. We made an uneventful landing and taxied in. No emergency services were used or ever seen.
PC-12 Captain reported returning to departure airport after noticing the torque gauge surging shortly after takeoff.