As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) FUEL CAP RETAINING SCREW LOOSENED AND CAP SEPARATED PERMITTING INTERNAL PARTS OF THE FUEL CAP TO FALL INTO THE FUEL TANK. THE FUEL CAP AND SCREW WAS FOUND ON THE RUNWAY. THE AIRCRAFT WAS CONDUCTING NIGHT CIRCUITS AT THE TIME OF THE OCCURRENCE.