As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - UNWANTED FUEL TRANSFER DURING FLIGHT. DETERMINED THE LEFT TANK WAS FEEDING INTO THE CENTER. RETURNED TO DFW AND LANDED WITHOUT INCIDENT. FOUND LEFT FUEL TANK FILL VALVE SWITCH IN OPEN POSITION. WHEN CLOSING FUEL PANEL DOOR GANG BAR DOES NOT SHUT OFF FUEL FILL VALVE SWITCHES. REPLACED HINGE ON FUEL PANEL DOOR. SYSTEM GROUND CHECKED NORMAL OPERATION.