Hang on, theres a big difference between a leaking fuel tank and punctured fuel tank.
Look around the ground under any vehicle. You'll see fluid leaks.
There's leaks and there's leaks! A slow ooze of liquid around a joint may well be deferable. I seem to recall operating with a known fuel leak - a while back now - if I remember correctly the engineers had to count the number of drips per unit of time. It doesn't even need the tank to not used.
In otherwords quite possibly a non event, but does depend if the appropriate maintenance checks were conducted.
pb