As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. DURING FLIGHT THE CREW OBSERVED UNCOMMANDED FUEL TRANSFER FROM THE CENTER TANK TO THE LEFT MAIN FUEL TANK. REMOVED AND REPLACED OUTBOARD FUELING SHUTOFF VALVE IAW AMM 28-21-02, FUELING SHUTOFF VALVE CONTROL UNIT IAW AMM 28-21-12, DEFUELING VALVE IAW AMM 28-26-01, DEFUELING VALVE ACTUATOR IAW AMM 28-26-11, AND FUELING MANIFOLD TUBE ASSEMBLY IAW AMM 28-21-10. LEAK AND OPERATIONAL CHECKED GOOD.