Sir - I have been following the investigation into the TW800 accident with great interest, and the two letters on the subject from Capt Pike and Mr Gambardella (Flight International, 13-19 August, P48) prompt me to draw attention to a passage in Lightning Protection for Aircraft (Fischer & Plumer, NASA pub 1008), P127, para 6.4.2, which discusses the phenomenon of explosive (as opposed to combustive) flame propagation in fuel-tank vent ducts.
The investigations discussed were based on electrical ignition and its consequences. Such explosive propagation can probably also be initiated in other non-electrical ways, however. I suspect that any small, but violent, detonation will do.
The point is that such explosive flame propagation is not stopped by flame arresters.
Paul Simison
Hickling, Norfolk, UK
Source: Flight International
