As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING RETURN LEG OF FLIGHT, ENGINES BEGAN TO SURGE AND OSCILLATE WHILE IN LEVEL CRUISE FLIGHT. CONTINUED BACK TO BASE FOR A PRECAUTIONARY LANDING. WHILE IN HOVER TO HELIPAD AREA, ENGINE OSCILLATIONS INCREASED AND NR 2 ENGINE LOW AND MASTER CAUTION LIGHTS ILLUMINATED AND NR 2 ENGINE COMPRESSOR STALLED. COMPRESSOR STALL EMERGENCY STEPS WERE COMPLETED AND LANDING WAS COMPLETED.