As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNWANTED FUEL TRANSFER. FOUND NR 3 AFT OVERRIDE PUMP DISCHARGE CHECK VALVE MISSING PIN FOR DRAIN HOLE. REQ PER MM 28-31-11 ITEM 1D. REPLACED CK VLV WITH PIN INSTALLED. PROBLEM PERSISTED. PERFORMED TANK ENTRY & TROUBLESHOOTING. FINALLY REPLACED DENSITOMETER, COMPENSATOR & TANK PROBE. RETURNED TO SERVICE WITH NO RECURRENCE OF UNWANTED FUEL TRANSFER.