Re: Engine fire extinguishers... do they exist?

From: (Brian A. Reynolds)
Organization: Rockwell Avionics - Collins
Date:         03 Sep 96 01:16:57 
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>Re: Engine fire they exist?

>Could anyone tell me if there are any fire extinguishers mounted
>inside or close to the engines in modern airliners? If there are
>any - how do they work? Any special gas, different to those used
>in regular fire extinguishers?

Requirements for power plant fire extinguishing systems is contained
in FAR/JAR/AR 25-1195 (Fire extinguishing systems) and 25-1197 (Fire
Extinguishing agents) and 25.1199 (Extinguishing agent containers)

So your questions in order:
1.   if there are any fire extinguishers mounted inside or close to
the engines in modern airliners?

25.1195(a)  Except for combustor, turgine, and tail pipe sections of
turbine engine installations that conatin lines or components carrying
flammable fluids or gases for which it is shown that a fire
originating in these sections can be controled, there must be a fire
extinguishing system serving each designated fire zone.

2. - how do they work?

Very well (sorry couldn't resist :).  Normal configuration is two
'bottles' of a fire surpressent, piping of the surpressent to the
designated areas, and a means of allowing the surpressent to move
from the bottle to the fire zone.  The bottles are pressurized, and
have a rupture disk which is pierced by an explosive opener.  The
expolsive mechanism drives the opener into the disk, allowing the
surpressent to flow from the bottle into the piping.  This is a 'one
shot' mechanism, very reliable, and the bottles are serviced at
regular intervelts.  There normally there are two such bottles per
engine, controlled by a single lever located in the flight deck
overheah.  Rotating the handle in one direction discharges one fire
bottle, and normal procedure is to then rotate the handle in the other
direction to discharge the second bottle.  This same handle also
operates the generator disconnect for that engine. These handles
simultaneously operate fuel and electrical cutoffs for the effected

3. - Any special gas, different to those used in regular fire

Halon was the gas of choice, but that is no longer 'politically
correct' and it is being replaced by 'otehr stuff.'  (sorry for the
technical jargon - but I don't know what the replacement is or how it
compares with halon.)