What was found
(CAN) THE AIRCRAFT RETURNED TO THE STATION AFTER 2 HOURS OF FLIGHT DUE TO FLIGHT CREW EXPERIENCED DIFFICULTY TO USE FUEL FROM TANK NR 2 RT. DURING INITIAL INVESTIGATION AN ACTUAL UNBALANCE WAS FOUND BETWEEN TANK NR 2R AND TANK NR 2 LT. ENGINES GROUND RUN CONFIRMED THE ABLITY OF FUEL TO BE TRANSFERRED FROM TANK NR 2 RT. FUEL FLOW EQUALIZER WAS ISOLATED AS PER M.E.L. AT NEXT LAYOVER THE FUEL FLOW EQUALIZER WAS REPLACED WITH 3 FUEL QUANTITY PROBES. THE FUEL PUMP FILTERS WERE CLEANED AND THE FUEL QUANTITY SYSTEM CALIBRATED.