What was found
DURING FLIGHT, THE CREW OBSERVED UNCOMMANDED FUEL TRANSFER FROM THE CENTER TANK TO THE LEFT MAIN FUEL TANK. REMOVED AND REPLACED THE OTBD 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 OPS CHECKED GOOD. AIRCRAFT WAS GROUNDED.