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

From: (Greg Croydon)
Organization: ViaNet
Date:         03 Sep 96 01:16:57 
References:   1
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Erico Oller Westerberg <> wrote:

>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?

You bet there are. All are part of a fire warning system, either
temperature sensitive of optical.

The engine area may be sensed by one or more heat-sensing loops, which
are flexible, stainless steel tubes containing a single wire centred
on a semi-conductor type material.  The loops are connected to control
units that monitor electrical resistance.  As the loop is heated, its
resistance decrease until, at a preset temperature, usually 500
degrees F, a nasty red light illuminates and bells/or robo-voices
start telling you that you are having a bad day.

The optical systems simply see bright lights in places they dont
belong, but are less sophisticated and prone to reacting to sunlight
seeping in, etc. Not used on modern aircraft.

The extinguishant comes in many different varieties, the most notable
being an interesting chemical that goes by the name,
monobromotrifluoromethane (CBrF3). This agent is not corrsive, and its
discharge does not necessitate cleaning of the engine or nacelle.
Relase of the agent is done by the electrical firing of an expolosive
discharge on the bottle containing the agent.

Most aircraft systems will have two bottles per engine, with the
capability of directing the agent to either engine.