1. There ain't no such thing as a crash-proof helicopter fuel tank. 2. Latest practice is to move the fuel outside the fuselage if possible, i.e. sponson tanks. For KR use, think of the wings as skinny sponsons. If you're familiar with the MH-53E/S80-M1, make that very skinny :-)
3. If the fuel has to be in the fuselage, put it behind the cabin with the strongest bulkhead in the A/C in front of it, i.e. Blackhawk. Also, use "Breakaway" connections on all fuel lines (boucou $$$) 4. All tanks do use a "self-sealing" inner bladder (think "bullet-proof", up to 20/23 mm) (more $$$$) 5. And, as I mentioned before, internal/external auxiliary tanks use foam or "Explosafe" aluminum mesh to prevent fuel from flying around in a crash. It doesn't stop the fuel from burning, though :-( Sorry, I don't remember the manufacturer/trade name for the foam. See: http://www.explosafe.com/contents/exploSys.htm Allen G. Wiesner KR-2SS/TD S/N 1118 (ex {involuntarily retired} Sikorsky Tech. Rep.) 65 Franklin Street Ansonia, CT 06401-1240 (203) 732-0508 flash...@usadatanet.net
