I've only just started to re-read the original BEA report, to clear up some of the tank 5 issues in my own mind.
Tank 5 is nominal 9090 litres. I haven't found the estimated value for the fuel leak yet, so I don't know yet how long it would have taken for tank 5 to empty through the leak. Does somebody already have the figure?
However, there has been a lot of talk about "overfilling".
Now, first of all, this is (was...) a normal practice for range or weight limited flights. Let me explain.
During refuelling, there would be an automatic cut-off for each tank, when the tank was about 95% full (fuel quantity sensor).
Afterwards, it was possible to add about 1500 litres, by a carefully measured "topping up" of each tank, to compensate for the 1 to 2 tons that would be used during taxying.
This "overfilling" and the resulting lack of airspace has been blamed for the 'oil-canning' (hydraulic shockwave) of tank 5, it seems.
Well, we now have a minor problem....
The BEA report states that only about 300 litres (about 500 lbs) was 'overfilled', and only into tanks 1, 2, 3 and 4, NOT into tank 5.
CJ