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Jerry,
I question the appropriateness of a Halon fire extinguishing system in the engine compartment. (or inert gas for that matter) While Halon is an excellent extinguishing agent, I suspect the ventilation rate in the engine compartment would limit its effectiveness to a very short time. While this may be enough to momentarilly halt the combustion process, the fire will reignite if the initial ignition source is still present or if hot surfaces generated from the fire are still hot enough to reignite it.
A common problem with the use of Halon or CO2 in compartment fires is that the ventilation points are not closed, allowing the extinguishing gasses to escape before the fire is quenched. Even when the ventilation is properly secured, the personel often open the door to make an inspection before the contents have had sufficient time to cool. This allows fresh air inside with the result of reignition from hot surfaces.
Halon is a good choice for the aircraft cabin since it is fairly non-toxic and won't be purged from the cabin too quickly (remember to close the vents as long as you can stand it). CO2 obviously won't work here due to its negative effects on the PIC.
I don't know what the industry standard is, but I would think that a dry chemical system would be more appropriate for the engine compartment.
Finally, it was my understanding that Halon was getting quite difficult to obtain as it is one of the banned CFC's responsible for Ozone depletion. I know the price has risen substantially and it is common to convert to a Halon replacement or to CO2 after the currently installed Halon systems are used.
I hadn't heard of the LIV fire you reffered to but I am involved in the case of a Sarratoga that had an engine fire shortly after take off. They managed to report it to the tower and turn around before it came through the firewall. They were overcome and crashed without further contact with the tower. Time is certainly not on your side with a fire up front.
Rob
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