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Engine fire on start-up


whirlygirl7
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I'm gearing up for my private pilot checkride in a Robinson R22, and I've been dissecting the emergency procedures so have a better understanding of the "whys"... I've been looking up more info on carburetor flooding/cranking/engine fire on start-up, but I still have this hang up with my curiosity because I don't know of any examples!

 

Has anybody every known someone to encountered this??

What was the cause, and how was it handled?? (since I don't usually have a wool blanket handy as suggested to put out a fire!)

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Over priming can cause a fire as there would be excessive fuel. If you manage to get it started it will suck the flames through the manifold and into the engine eliminating the fire. Then it should be shut down and inspected. If this does not work, grab the extinguisher and GET OUT OF THE HELICOPTER! I also would not recommend trying to put it out as suggested in the manual because you are increasing your personal risk of being injured. If all occupants are out and no one is on fire, use the extinguisher to put it out. If that fails. Stand at a safe distance and watch it burn while you call the FD!

 

Edit: spelling

Edited by nightsta1ker
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nearly all lycomings utilize an updraft design intake system (carb or fuel injector sits at the low point below the engine) when you prime the engine the fuel runs down the intake runners and dumps on the ground or collects in the runners and around the carb/fi. When you hit the starter and ignite the fuel even though it is up stream the cylinder it is possible that the hot combustion will ignite all that fuel you primed into the runners. If the engine doesn't start but the fuel does ignite you may have a fire that swarms around the carb where lots more fuel is! Many airplanes have burnt because of this... that's why they recommend continuing to crank the engine and "suck" the flames into the cylinder keeping the fire from burning ahead of the intake valve.

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Awesome explanation! My only question is, how can you tell if there is a fire until it's too late? There is no fire warning system on the R22, and the engine is behind you, so unless you are tail into the wind you will probably not notice the telltale signs of smoke.

Edited by nightsta1ker
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if the engine started... there shouldn't be a fire. Obviously you are always on the look out for a fire on or in the aircraft when it is running. If it didn't start and you smell burning.. that's your cue. Just cause there is a fire doesn't mean it will damage anything... if it is extinguished quickly. Alot of times you may get a flash of flame and it will burn out quickly as it burns the raw fuel... on the carb engines the fuel in the bowl may keep the fire going long... that is usually when damage occurs.

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  • 3 months later...

Awesome explanation! My only question is, how can you tell if there is a fire until it's too late? There is no fire warning system on the R22, and the engine is behind you, so unless you are tail into the wind you will probably not notice the telltale signs of smoke.

 

Have always wondered about this too. Will you notice a fire in abnormal engine operation?

Or do you have to look back at the engine to see/notice a fire?

I have not encountered anybody that had this happen to them or know about it..

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I would say that the primary indicator would have to be smoke. But what if the helicopter is pointed into the wind and the smoke is being blown away from the cabin? You can't see the engine compartment from inside an R22. I still don't know how, in some situations, you would know you are on fire until its too late.

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  • 7 months later...

I would say that the primary indicator would have to be smoke. But what if the helicopter is pointed into the wind and the smoke is being blown away from the cabin? You can't see the engine compartment from inside an R22. I still don't know how, in some situations, you would know you are on fire until its too late.

 

Simple fix really. After you start it up, stick your head out the door and look back. No smoke/flames? Good to go.

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I have had fires in a number of different aircraft, on the ground and in flight.

 

A fire during engine start can occur in a piston engine, or a turbine. The basic procedure is the same. Shut off fuel and continue motoring the engine.

 

Most often you will be aware of an engine fire on start because someone will tell you.

 

If the fire does not extinguish by motoring or cranking, and that is exactly what will happen if the fire is external to the engine (such as excess prime, a failed fuel line or ruptured flow divider diaphragm, etc), then by all means get out and fight the fire if you are able to do so.

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Simple fix really. After you start it up, stick your head out the door and look back. No smoke/flames? Good to go.

 

Exactly! I always start up with door open and headset off. I want to see and hear everything at first, bearings, sound of the belt engaging, anything that sounds "different" than it usually does. Plus if you don't have AC it's cooler. My door gets closed and latched when the controller says go.

 

PS, I know what it says in the start checklist.......

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Goldy, that was a very auspicious Post Script. A checklist or emergency procedure should never supercede the wisdom that comes from experience or actions that are inspired by common sense and dictated by the situation.

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