As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) WHILE IN FLIGHT PILOT NOTICED NR BEGIN TO DROP. HE INITIATED AN AUTOROTATION, HEARD A LOUD BANG, AND THE RPM CAME BACK UP. UPON LANDING FLAMES AND SMOKE WERE NOTICED IN THE ENGINE BAY. PILOT EXTINGUISHED FIRE AND DETERMINED IT WAS THE STARTER GENERATOR. IT APPPEARS THE BEARINGS SEIZED WHICH WAS BRINGING DOWN THE ENGINE RPM UNTIL THE SG SHAFT SHEARED.