What was found
*SDR FILED OPEN* FUEL APPEARS TO BE MIGRATING FROM L INNER TO CENTER TANK AT 2-300LBS/HR.(1300LBS OVER 4 HR FLT.) AIRCRAFT OPERATED IN PAYLOAD, (CTR AND TRIM DEACTIVATED.) VERIFIED FUEL IS TRANSFERRING SLOWLY BETWEEN LEFT INNER TANK AND CENTER TANK USING LEFT INNER TANK BOOST PUMPS. CLOSED FUEL CROSS-FEED VALVE AND LEFT HAND INNER/CENTER ISOLATION VALVES. FUEL STILL TRANSFERS. RAN BOTH INNER AND #1 CENTER TANK BOOST PUMPS AT THE SAME TIME, FUEL STILL TRANSFERS. SUSPECT PIPE LEAK INSIDE CENTER TANK IN THE PIPE BETWEEN THE #1 CENTER TANK BOOST PUMP AND THE LEFT INNER TANK PUMPS.