Fire
Most encounters with fire in aircraft end as non-events. Even the non-events would not happen if the pilot makes a no-go decision because of empty holes in the panel. Flying with a known deficiency is just looking for trouble. Preparing for an in-flight smoke/fire occasion should begin with carrying a handheld radio that will give you communications with the electrical system off. Having a small halogen extinguisher is additional insurance.

There are four kinds of aircraft fires, engine start, electrical, in-flight and post-crash. A different checklist is required for each type. In flight aircraft fires are far more rare than ground fires from engine starts. Next in frequency is an engine fire caused by failure of an engine compartment component. Insulation, adhesives and fabrics are the usual fuel once ignited by burning avgas and oil.

Basic fire procedure is to remove the source of combustion. In electrical fires you can shut down the master switch. Done quickly enough it may not have ignited other inflammables. Your best cockpit extinguisher is the Halogen 1211, which is soon to be unavailable.

Electrical fires have an acrid smell with possible white smoke. Begin by shutting everything off with the master. Then shut off all individual circuits. It may be better not to turn anything on but if conditions require, turn on the master and then re-energize each circuit one at a time in an effort to isolate the problem. Handheld radios and GPS become worth their weight and cost in this situation. Don't fly any longer than necessary.

Black smoke warns of oil while fuel makes orange flames. Respond to a fuel fire by pulling the mixture, shutting off the selector, and applying full throttle to use up the carburetor fuel. Shut off cabin heat. Point the nose to the ground and if possible get the flaps down so as to minimize your ground contact speed when you level out.

Post-crash fires are more dangerous than the crash itself. Most deaths come from some and carbon monoxide inhalation. Fill the cockpit with Halogen before exiting. Good maintenance is still the best fire insurance.

Fire in an aircraft will get your attention. Cut off the source of fuel be it gasoline or electricity. Be in an emergency descent configuration for as long as smoke exists. You must decide whether to dive or slip. The slip is most likely to keep the problem away from the cockpit but may take longer to lose altitude. Most engine fires occur on the ground in the winter. The engines are over-primed and a backfire can ignite excess fuel. Shut off the fuel via the mixture and the selector valve. Keep cranking the starter to suck the fire into the exhaust system and if the engine starts so much the better. Give maximum throttle to use up available fuel and perhaps blow out any existing flames. Radio for help and be prepared to bail out. Over-prime with the throttle is most likely to create the ground fire hazard.

Every second of the fire's existence is a prelude to disaster. In the event of a fire there is no time for a checklist. While there are more electrical fires than engine fires, more fatalities result from engine fires. A pilot trained for emergency situations will have a better chance of maintaining control of the aircraft.

Engine fires are mostly caused by exhaust system component failures. Cylinder failure runs second as a fire cause. Defective maintenance is third. Accident specialists find that the source of a fire is usually at the site of the last maintenance work. 20% of in-flight fires are due to maintenance. On average two in-flight fires occur every month. Less than five fire fatalities occur per year.

A small flight kit sized halogen extinguisher can still be obtained. Get one. Structural failure or pilot incapacitation is an imminent outcome of any fire that is not quickly put out. Get down making emergency descent with flaps down if possible. You will get down just as quickly. Otherwise slip as much as possible. Get the fire stopped by shutting off electric masters and fuel supply. Smoke can be removed from light planes by using cockpit and wing vents.

What To Do:
--Engine fire -- shut off fuel; full throttle
--Electrical fire -- shut off master, use extinguisher, ventilate
--Cabin fire -- ventilate, extinguish, use liquids
--Emergency descent flaps, slips as possible.
--Gear up/down, ditching decisions.

Fire is fueled in aircraft by either gasoline or electrical energy. Black smoke usually indicates gasoline/oil and white smoke + a distinctive odor is electrical. Most electrical fires will die when the master switch is cut off. Fuel fires in the engine compartment can be cut off by the mixture, fuel pump and fuel cutoff valve. In any event get on the ground as soon as possible.

Getting to the ground quickly and keeping the fire and smoke from the cockpit requires that an extreme nose high slip be set up. A descent rate of well over 1000-fpm can be achieved with full rudder application. IAS may be kept below 50 in this situation. Release rudder at the last moment and hold the aircraft off the ground to land as slow as possible. A deliberate groundloop will bring the aircraft to a quick but abrupt stop. Get your doors open before you land. This might well be something to practice at altitude with your instructor. Aircraft fires in flight are rare but they do happen.

An oil fire is more serious because you cannot shut off the source of fuel as you could with a gasoline fire. The engine compartment is probably the best engineered part of the aircraft. The firewall will contain the fire unless it gets around the nacelle or firewall. The most likely source of an engine fire is in the exhaust system and in old weakened fuel lines and hoses. The inability to make a preflight inspection of such weak areas is where you, the pilot, must put your trust in a maintenance program that includes periodic hose changes.

An exhaust leak will usually vent heat overboard with the cooling air. If an exhaust fire should occur, the heat can be reduced by enriching the mixture. A preferred option might be to pull the mixture to stop the engine. Once a gasket starts to leak it will only get worse. An oil leak is more likely to be in an area of low airflow.

Aircraft fires on the ground usually occur during the starting procedure. The use of excessive (4 pumps) throttle prime means that the carburetor bowl will overfill. The gasoline flows out the vent in the top, and accumulates at the air intake or elsewhere. As the starter turns the engine a slight backfire can ignite the fuel in the engine compartment. The instant smoke appears, pull the mixture, shutoff the fuel selector valve, continue to crank the engine. If the engine starts, apply full brakes and full power us speed consumption of gasoline in the carburetor. If the engine does not start, continue cranking since the vacuum formed by the pistons will draw flames up the exhaust and use up the fuel in the system by drawing it into the engine. Prepare to exit if this does not work. You might consider alerting ATC to send the airport fire crews. About 6% of all accidents involve in-flight fires. Age of the exhaust system and fuel system hoses is the greatest single cause.
Aircraft Fire Extinguisher
Use only a B-C type the A type corrodes aluminum.

Fire Situations
--Start-up fire without engine running
Use starter to keep engine turning but shut off all fuel. Suction of pistons will draw fire into engine and exhaust system.

--Start-up fire with engine running
Full throttle and cut off all fuel sources. Uses up fuel and can blow out fire. Electrical off.

--Cabin fire
Electrical off, isolate cabin from engine compartment, extinguisher, land.

--Engine fire aloft
Mixture off, all fuel off, electrical off, flaps down, isolate cabin, emergency descent
Consider maxim performance slip or power dive to keep fire from cabin.

PTS Emergency Descent
 (No longer required but nice to know)
1. Fastest practical descent. within aircraft limitations
2. Clearing turns
3. Making 30-40 degree banks during descent will increase descent rate
4. Descend at structural cruise speed (yellow-green) or full flaps at top of white arc.
5. Divide attention and ignore distractions
6. Checklist
7. End exercise when procedure is established to prevent shock cooling.

En route Engine Failure
1. Selector
2. Pump-pressure
3. Mixture
4. Alternate Air
5. Gauges

Select:
--Golf courses
--Unplowed brown fields
--Grassy fields
--Parking lots
--Access roads
Avoid
--Dark brown (wet) fields
--Plowed and planted fields
--Power lines

 

Continue To Next Page