As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ENGINE UNCONTROLLED ACCELERATION OCCURRED DURING FLIGHT, CAUSING A MAIN ROTOR OVERSPEED TO 110 PERCENT. PILOT REDUCED THROTTLE TO MAINTAIN RPM WITHIN LIMITS AND LANDED. GROUND RUN SHOWED THE ENGINE CONTINUED TO ACCELERATE PAST IDLE DURING START SEQUENCE. FUEL CONTROL SENT FOR ANALYSIS WITH 55.6 HRS REMAINING.