As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING GROUND HANDLING OPERATIONS, THE ENGINE EXPERIENCED AN UNCOMMANDED ACCELERATION. THE ENGINE DID NOT RESPOND TO THROTTLE OR SHUTOFF LEVER INPUT. THE CREW SECURED THE ENGINE VIA AIRFRAME FIREWALLSHUT-OFF. PWC WILL INVESTIGATE THE EVENT AND ADVISE OF ROOT CAUSE, ONCE ESTABLISHED.