PENKO: as Tyropicard says please revisit the Air Transat A330 fuel leak incident. The problem lies with establishing whether the leak is from the actual TANK wall or some of the piping from it!
Incidently, the fuel leak procedure for the A330 is a bit more "punchy" than that for the A320 and may have gone some way to explaining the Air Transat`s crew behaviour.
Many years ago the B707 did in fact have a fuel leak procedure which encouraged the use of the leaking tank prior to all the fuel from it being lost however the more modern philosophy today does not allow this for very good reasons.