As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING ROUTINE MX, THE ENG COWLS WERE OPENED & THE SHEARED SECTION OF THE ENG CRANKCASE THRU BOLT WITH THE NUT STILL ATTACHED, FELL OUT OF THE ENG COWLING. THE SHEARED THRU BOLT WAS LOCATED AT THE FLANGE OF THE NR 6 CYLINDER ASSEMBLY.