Ron, I'm curious if Halon has a place at all in a/c. I agree w/ you in
regards to use under a cowl. But also if it Displaces O2. Wouldn't it starve
you of O2 as well if you blew off a bottle in your cockpit

Jarret,

 

I assume this was directed to me (Rob).

 

In my previous reply I explained that Halon does not work by displacing O2. However, the byproducts of its use on fire are not as healthy as good clean air either. 

 

A fire in the cabin just does not leave many good options. For obvious reasons, flooding the cabin with oxygen displacing agents, like CO2 or nitrogen is not going to give favorable outcomes. Since the volume of most GAO cabins is quite small, one would need to use a hand held CO2 sparingly to avoid asphycsiation and even then it would be difficult to direct this to the necessary spot behind the instrument panel. Water is rather heavy for an aircraft and is problematic on electrical fires.

 

This only leaves two common agents, dry chemical and Halon or its replacements. Dry chemical works very well as long as the spray reaches the base of the fire and it also lasts a long time. The downside is that fuels which aren't coated with the chemical will continue to burn.

 

 The original Halon products worked very well as an extinguisher. Since it is a gas, it readily flows into the combustion zone even when the pathway is indirect. It can be used to flood a volume or be applied locally in the same manner as a hand held CO2 extinguisher.

 

Small amounts of the reaction products of Halon over brief periods of time are not a significant problem. However, if one is exposed to higher concentrations or extended periods of time, dizziness, vomiting and/or unconsciousness can occur. Obviously not good for the PIC. I don't really know much about Halon replacements. Perhaps they are more toxic than the original Halons.

 

You could certainly fight a much larger fire with Halon and survive in the cabin than you could with CO2. Dry chemical would allow you to fight an even larger fire, but only if you could discharge the powder directly at the burning fuel. I don't know where the Halon replacements fall in this.

 

Rob