d747
I think you will find when an aircraft is flying at 200mph or more as this Concorde was, any fuel leak will atomise especially around the edges of the flow and could be ignited . This is why when dumping fuel, all sorts of precautions are taking to prevent the stream igniting.
From what I remember about fuel fires is that, it is the fumes that burn not the fluid, and perhaps in the TWA case it is at 53 degs [ F 0r C ?] that fuel starts to vapourize sufficently to give, above the fluid, a fuel/air mixture that will ignite given a spark source