What was found
RUNNING TANK TO ENGINE ON ALL 3 ENGINES. ALL FILL VALVES WERE CLOSED BUT FUEL LEVEL IN TANK 1 WAS NOT DECREASING. VERIFIED ON GROUND WITH TANK 2 AND 3 TRANSFER PUMPS ON THE NR1 TANK QUANTITY INCREASED WITH THE FILL VALVE SELECTED (AND INDICATED) CLOSED. UNCOMMANDED FUEL TRANSFER WAS APPROX 1000 LBS EVERY 7 MINUTES. R & R THE NR 1 MAIN TANK FILL SHUTOFF VALVE CONTROLLER IAW AMM 28-21-02-4. NO HELP. UNCOMMANDED FUEL TRANSFER STILL TAKES PLACE AT THE SAME RATE. TANK ACCESSED AND FOUND CRACKED LINE AT TEE FITTING FROM NR 1 TANK FILL VALVE ON TOP SIDE OF WELDED FLANGE. REPLACED IAW MM 28-00-00-2-0 & 28-00-00-4-0. PRESSURISED REFUEL/CROSSFEED MANIFOLD USING NR 2 TRANSFER PUMP, NO FUEL TRANSFER EVIDENT AFTER 10 MINUTES.