"....Further, on inspection of another ac in theatre a small hole was found in the pipe. The pipe is welded to several brackets which are themselves attached to the supporting rib wall and the hole was close to one of the welds.
It is not uncommon for there to be pressure spikes during the refuelling process as refuel valves are closed elsewhere during the process. It is possible that repeated pressure spikes or repeated applications of normal pressure during either ground refuelling or AAR might have lead to the weakening of the weld and the subsequent hole. Atomised fuel could then escape into the space. What is missing, however, is an ignition source and that is a bit of a stumper.
If we assume that somehow ignition took place it is conceivable that the fire could then heat a fuel tank that is positioned in the wing root area, and this may have led to the explosion.
What is interesting to ponder is that the same airframes are generally being used for the Gulf theatre due to their fit. These few frames would be used in AAR more frequently than the other ac in the fleet. This argument might also be backed up by the fact that the fuel pipe hole was found in another Gulf ac in theatre."
I know the above quote is supposition, but this was known when AOC2Gp ordered nimrod crews to continue AAR sorties 4 days after the tragedy. I have no idea if the BoI has since discovered the source of the ignition which led to the explosion. What I cannot understand is the decision to go ahead with a single skin AAR system which was designed on the back of a piece of paper 25 years ago. Furthermore, to protect the crews from a fuel tank explosion it would be relatively simple and cheap to fit a nitrogen inerting system to the current nimrod fleet and the MRA4 replacement.
Safety does not appear to have been given the highest priority here.