What was found
(CAN) DURING REFUELLING USING SINGLE-POINT SYS & FILLING BOTH MAIN (WINGS) & VENTRAL TANK. AS VENTRAL TANK REACHED 1.5 TO 3 QUARTERS CAPACITY FUEL WOULD FLOW THROUGH VENT SYS INTO LT SURGE TANK & SHUTDOWN BY CLOSING MAIN VALVE. COMPLETION OF REFUELLING COULD ONLY RESUME ONCE SURGE TANK EMPTIED & VENTRAL TANK FUELED VIA FUELING CAP. ON REMOVAL OF VENTRAL TANK, DISCOVERED RT VENT FLOAT INADVERTENTLY GLUED TO VALVE BODY & NEEDLE HARD TO OPERATE. BOTH CONDITIONS LEFT RT VENT VALVE OPEN DURING ALL CONDITIONS CAUSING FUEL TO ENTER VENT PIPING THOUGH NONE EXISTED. FLOAT REMOVED & NEW NEEDLE INSTALLED, OPS OF VALVE CHECKED FOR SMOOTHNESS & PROPER SEALING OF NEEDLE TO SEAT. MODIFICATION (25G137A) EMBODIED TO INCORPORATE AN ACCESS PANEL FOR EASE OF INSTALLATION OF VENT VALVE ASSY & ENSURE PROPER SEALING & INSPECTION OF AREA. INTEGRITY OF VENT SYS LEAK CHECKED. COMPONENTS WERE INSTALLED & VENTRAL TANK CHECKED FOR LEAKS & PROPER REFUELLING. ALL SYSTEMS SATISFACTORY.