As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CHECK VALVE BETWEEN THE AUXILIARY FUEL TANK AND THE RT MAIN TANK FAILED, ALLOWING FUEL FROM THE RT MAIN TO DRAIN INTO THE AUX TANK AND OVERFLOW FROM THE FILLER NECK. THE PUMP AND VALVE ASSEMBLY IS INTENDED TO MOVE FUEL FROM THE AUX TANK TO THE RT MAIN TANK AND PREVENT REVERSE FLOW. RECOMMEND A POSITIVE SHUT OF VALVE BETWEEN THE RIGHT MAIN TANK AND THE AUX TANK PUMP TO PREVENT AN IN-FLIGHT DRAINING OF FUEL FROM THE RT MAIN TANK.