As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ALTERNATOR WAS REMOVED TO CHECK FOR INSTALLATION OF NUT ON SPLINE DRIVE. COTTOR PIN WAS BROKEN AND NUT WAS BACKED OFF THE SPLINE. BOTH THE NUT AND COTTER PIN WAS FOUND INSIDE THE ENGINE SPLINE GEAR. ALTERNATOR WAS SENT TO MANUFACTURER FOR OBSERVATIONS.