Aircraft Engine Fire

[ottawa]

The intent of this questionnaire is to solicit existing information and experience that would improve training and readiness of airport fire fighters for incidents with both modern technology and legacy aircraft.



Uncontrolled engine core fires (core & tail pipe)

Uncontrolled engine core fires in high bypass turbofan engines present a difficult challenge to airport firefighters. Since the fire is burning within the turbine casing and exhaust nozzle, pulling the fire handle to discharge extinguishing agent into the space between casings and cowls would seem to be ineffective.

Question:

Could you please confirm that pulling the fire handle may also make it impossible to dry motor the engine, which is the quickest way of extinguishing most tailpipe fires?
In case dry motoring does not work, would you recommend flooding the intake and/or exhaust with aqueous film forming foam (AFFF) using large monitors, or dry chemical powder, or clean agents such as Halotron?
What would be the recommended extinguishing agent application technique? Would directing the streams to the core annulus be more effective?
In situations where fuel control to the engine is malfunctioning, what are the alternate means of cutting off fuel to the engine?

Accessory compartment fires

Fires in the accessory compartment are usually best controlled by the onboard firefighting agents (Halogenated products) initiated by the fire handles.

Question:

In situations where the onboard firefighting system malfunctions or is unable to suppress the fire, manual firefighting will have to take place. Which locations in the nacelle would be expected to be the seat of the fire? Are there external indicators, e.g. Infrared signatures that would aid in detection and assessment of the magnitude of the fire?
In order to access the seat of the fire what would be the recommended access point? Would you recommend using service ports such as oil fill point’s access panels to inject extinguishing agents?
Would you recommend the use of a piercing applicator to inject foam, dry chemical or clean agent into the accessory compartment? In the affirmative – what reference points would you use on the nacelle?
What extinguishing agents would you recommend?

Inability to shut down

On two occasions, two large frame aircrafts (A340 & A380) experienced an inability to shut down their engines while on the ground during emergencies.

Question:

In case of control/FADEC malfunction and fuel spar valve remaining open, what alternate means of shutting down the engine could you propose?
Would complete flooding of the engine core be the only viable option to shut down (terminate combustion in) an engine whose command & control has been lost? Would this be possible at idle and high power? Could engine stall be induced and at what risk?
Due to the design of high bypass turbofan engines, is flooding realistic? In the affirmative – what type of application technique. e.g. location, droplet size would you recommend?

[lomapaseo]

A very compledx question where one aqnswer does not fit all.

My suggestion is to parse this down to one question at a time if you really want to cover all possibilities.

In general, as long as there is a means to limit the source of fuel (spar valves etc.) then prioritize that action and protect the critical aircraft parts from excessive heat. That should keep the fire from spreading beyond the engine.

Damage cost is not an issue here but spread could affect cabin safey and or threaten fuel tanks. If you can stabilize that threat than you have lot's of time to try what you please with the engine.

Generally most engine fires will expend their source of fuel within minutes (petrol and oil) so ifr you protect the aircraft f9or that time period you have greatly reduced the safety risk.

Historically the most difficult engine fires are those where the spar valve can not be shut off starving the fire or the fire has progressed beyond the heat shield into the pylon.

Fires which are inpervious to shutting the spar valve are those where oil metal, or combustible internal materal is involved.

examples are : compressor titanium fires, magnesium accessories, or composite reverser cascades, In these cases the fuel is typically used up in minutes even though you are very unlikely to be able knock it down in that period of time.

As for shutting down running engines without shutting off the fuel I've seen blankets and/or lots of water work sometimes. But you may have lots of time to work on this as long as nobody goes near it. (The World Airways DC10 in Boston harbor comes to mind). If you are going to use water, try and aim an intense solid coulumn just outboard of the center body/spinner. That's the only way you can get it into the core (fan engines are designed to shed 90% of water spray out the fan ducts)

Ok that's enough for the time being to start the thread discourse

[dash6]

Part 1 What aircraft type? Is the starter electric or pneumatic? In general,the Fire handle/switch has no effect on dry cycling;its a function of the starter system.If the fire is during the engine start procedure,the crew will dry cycle the engine as part of the drill.Keep putting them out!:)

[glum]

We always have big carbon dioxide extinguishsers on the dispersal. If the engine catches, then the advice is to open the valve fully and direct the flow into the engine from as close as you dare!

For accessory compartments there are 'fire access' panels on the cowling, indicating where extinguishant should be directed if the on-board systems fail to quench a fire.

Pulling a fire handle shouldn't stop an air-start engine dry cycling, as it is intended to shut off fuel, oil and electrical connections.

As far as I'm aware, fuel systems should have two fuel valves in line from the tank to the engine, so there should always be two valves able to check the flow of fuel. Maybe that's changed on newer aircraft, as I can't see how else the A340 / A380 could be in a situation where they cannot shut down their engines?

[Checkboard]

Pulling a fire handle shouldn't stop an air-start engine dry cycling, as it is intended to shut off fuel, oil and electrical connections.

In an airbus, pressing the engine fire pushbutton cuts off the FADEC power supply, which would prevent a motoring sequence.

[tom775257]

Another thing, on the Airbus I thought that the fire push button cuts of Hydraulics, Electrics, Air and Fuel.. thus would not allow dry cranking as Checkboard said due lack of FADEC power, but also lack of air pressure available.

Regarding tail pipe fires, obviously it is much better to dry crank the engine and put the fire out. From my understanding, foam and dry powder will essentially destroy the engine. I had one tail pipe fire on A320 at shutdown and had to work hard to convince 'fire one' not to discharge any foam down the engine whilst the captain was carrying out a dry crank (which soon put the fire out). The only indication we had was the ground crew frantically waving at us.

The bigger problem would be if you had a tailpipe fire on engine shut down (like we had) but a non-functioning APU, therefore unable to dry crank. I would think ideally if you could use something non-corrosive to put the fire out it would be much appreciated!

Certainly a tail pipe fire is a different kettle of fish to a general engine fire and it isn't worth destroying the engine in a rush to put the fire out (Fire where fire should be essentially).