A300boy
Hi TopazBlue
I sympathise with your situation and worries ! I fly the Airbus A300 which is a very similar aircraft to the A310 with just about identical fuel systems. I doubt the leak was overboard and suspect it was internal between the fuel tanks which would mean one of the tanks would be unusable making the range of the flight around 1 to 2 hours flying shorter if the tank had to be empty! This would be caused by an internal non return valve not working properly.