As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING 50 HOUR INSPECTION. ATTEMPTED TO CONNECT EXTERNAL POWER AND FOUND TOP SMALL CONTROL PIN, LAYING IN BOTTOM OF RECEPTACLE. ATTACHING NUT WAS FOUND IN THE BOTTOM OF THE RELAY BOX. WIRE WAS FLOATING LOOSE IN BOX. APPARENTLY, NUT BACKED OFF DUE TO POSSIBLE VIBRATION. REINSTALLED PIN WITH NEW LOCK WASHER.