As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ON ENGINE START PILOT NOTED A BANG THEN THE STARTER MOTOR SPUN UP FAST. HE GOT OUT TO INVESTIGATE AND FOUND THE BENDIX GEAR LAYING ON THE GROUND. THE GEAR SHAFT SHEARED ON THE FWD END IN SIDE OF THE STARTER HSG. IT APPEARS TO HAVE BEEN CRACKED FOR SOME TIME. A NEW STARTER WAS INSTALLED.