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Engine Fire

Sheldon

Sheldon

Well Known Member
Last Friday, after a nice hour flight around my home field (St. John's KSJN), the day became a real bummer. Long story short. After refueling, it was a typical HOT START situation. Being impatient and in a hurry to put my plane back in the hanger, I kept cranking & over primed with the throttle. Engine flooded, backfired and caught on fire!

engine%20fire%20005%20(Medium).jpg


Lucky Gary was there that day & with an extinguisher, he put out the fire in time before I might have lost my entire plane.

Leasons learned:
1. Being Impatient NEVER WORKS...!!
2. Wait for engine to cool down before trying a re-start...
3. If flooded, See #2

Sheldon RV6A N858SB
 
Been there, done that.

...except in my case I lost some of the fabric on the belly of my airplane and the flames made it to my legs (and fuel selector valve) for a moment. I was fuel injected and the fuel was running out of the exhaust onto the ground.


After that I learned to NEVER run the boost pump on a hot restart. And I usually try to locate the fire extinguisher and leave the seat belts undone until it's running.
 
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I've done the exact same thing with a Super Decathlon - and learned how to repair fabric and re-dope as a result.
 
when you saw flames did you stop cranking or keep cranking? based on your story it sounds like you stopped cranking

then again, i'm making the bold assumption that it was of course going to fire up for you
 
Bummer!

This very reason is why I NEVER use the accelerator pump to prime a carbureted engine. Always use the primer! There is always a possibility of a fire when starting a flooded engine, but injecting the fuel in the clyinder intake port using the primer will greatly reduce the risk.

If the engine is hot, you have already primed a few times and still cant get the engine to fire you can try priming while the engine is cranking, that way the fuel will get sucked in the cylinder instead of running out of the carb. If the above does not work then the engine is most likely flooded and you should wait for about ten minutes for the starter to cool then skip the priming, open the throttle all the way and crank the engine to clear out the cylinders and intake tract.

Sorry about the damage, I hope you get it repaired and flying soon!
 
General Comment

I've seen many on this list advocate that a primer circuit isn't needed and carbureted Lycoming's prime just fine in RV's by pumping the throttle.

For the record, John Deacon has indicated in past APS news letters that this technique for starting is an absolute no-no and will eventually lead to an induction fire. Most may get away with it, but someone will eventually get burned!

Similarly, I feel the same way about the inclusion of the sniffle valve on forward induction injected engines. To leave it out is a bit penny wise and pound foolish. Most may get away with leaving it out, but someone will have an induction fire eventually.

Skylor
RV-8
 
My experience has been you can bet any hot engine after shutdown is going to be vapor "flooded". True for Carb or FI.
I've found the best way to start out for restarting any hot engine is WOT and mixture at ICO. If it fires within 6-8 blades then Rich with MIX and pull the throttle back. If it doesn't fire, then you're not flooded so attempt start as you normally would.
An accelerator pump carb is only your "friend" if the engine is cold. With a hot engine, moving the throttle forward just once dumps a lot of raw fuel into the filter housing and you can assume you'll be cranking way to much vapor to get it started unless you place the mixture in ICO. Leaving the throttle "cracked open" doesn't allow enough air into the inlet to get a combustible mixture... thus you remain "flooded".
 
rv9av8tr said:
My experience has been you can bet any hot engine after shutdown is going to be vapor "flooded". True for Carb or FI.
I've found the best way to start out for restarting any hot engine is WOT and mixture at ICO. If it fires within 6-8 blades then Rich with MIX and pull the throttle back. If it doesn't fire, then you're not flooded so attempt start as you normally would.
.
Click to expand...

How can you get WOT without the accelerator pump sending fuel into the airbox when performing a flooded start ?
 
Thanks for posting its a good reminder.

I have to actually go to idle cutoff for a hot start- then push the mixture in after it catches. I never prime or use boost pump for cold starts either. I always have plenty of fuel. Everyone has to find what works for them. Glad I recently got an extinguisher.
 
keep cranking??

bkthomps said:
when you saw flames did you stop cranking or keep cranking? based on your story it sounds like you stopped cranking

then again, i'm making the bold assumption that it was of course going to fire up for you
Click to expand...


Never had this happen but I've been advised that if this happens, DON'T STOP CRANKING. If you keep cranking you will draw the flames into the intake and can avoid a fire... wondering if this is effective.
PS An extinguisher is mandatory on Canadian a/c.
 
777Dave said:
Never had this happen but I've been advised that if this happens, DON'T STOP CRANKING. If you keep cranking you will draw the flames into the intake and can avoid a fire... wondering if this is effective.
PS An extinguisher is mandatory on Canadian a/c.
Click to expand...

Know of an intake fire where the fuel had exited the filter are and pooled on the cowl, cranking the engine in this case did not work
 
petersb said:
How can you get WOT without the accelerator pump sending fuel into the airbox when performing a flooded start ?
Click to expand...

1. ICO
2. Crank the starter
3. Advance throttle to stop


The shot of fuel will be drawn up into the engine and ether burned or swept overboard as part of the existing rich mixture.
 
Normally my HOT-START procedure is: leave the throttle closed (don't prime or crack the throttle) crank the engine and slowly push in the mixture... When the engine finds the mixture it likes, it starts.. Then open the throttle as needed.. Works most all the time. However if I miss this 'exact' time (example: pushing in the mixture too fast) it's too late.. Then it's time to leave it to cool down..
My impatience got the best of me when it didn't start, and I over primed via throttle and kept on trying to start it...

When it back fired I didn't think anything of it. I quit & left the plane to go into the office for a drink of water. Upon returning I saw smoke coming out of the cowl. That's when I yeld to Gary for the extingushier...

I have been out to the hanger only once since. I took off the cowl, nose gear fairing and the filter box. I brought the filter box home along with the melted K&N air filter inside it.

As of yet, I haven't been back out to the hanger to access the damage more deeply.. I will be doing that soon.. Hopefully the damage isn't too bad in that I can have my baby back in the air soon.. Will keep posting as to what I find & would be open to any suggestions as to what to do, check, etc..

Thanks for the support in advance and I hope my experience keeps others from having the same problem...

Sheldon
 
I feel your pain...

Been there. Left mine on the other side of the country for about 6 months before it was fixed. http://www.vansairforce.com/community/showthread.php?t=92042

Mine was due in large part to a faulty carb which led to a flooded engine. Even though I had kept cranking just in an attempt to start, I didn't even know I was on fire until I got out to push the plane to parking. Definitely more conscious of flooded starts now.
 
Wow Matt... Your pictures make my problem seem not so bad... I went out to the hanger today (and will tomorrow) cleaning up and checking out the damage further...
Sheldon
 
Well I finally got all repaired and am back in the air! Boy! Does it feel good after being down for 2 months. The damage wasn't as bad as first inspected. Repairs came easy (new fuel lines, all rubber in the engine intake & oil return lines, replaced the scat tubes, etc.) Clean up from the smoke took lots of time. The fiberglass repair on the air filter box was straight forward but not so on the lower part of the cowl. Just couldn't get the results I wanted. So I had the brain storm of replacing the damage with metal.
Picture attached shows this. A backing plate with nutplates for attaching. The paint is temporary just to get me back in the air, ordering correct paint now.
After many test runs and finally some flights, all seems good.
Sheldon
https://picasaweb.google.com/lh/photo/Z1GE9IR__FsVFWkVWxREvNMTjNZETYmyPJy0liipFm0?feat=directlink
 
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Your photo link did not work for me.
Last November... I lost my entire plane... when the fuel lit off.
It can happen so fast. Cranking advice you ALWAYS hear about is pretty pointless when gas has dribbled downward. Time is wasting and you can't get any visibility on what is happening.... and you are STILL in the AC.
Halon or other extinguisher as FAST as possible is the advice I go with. After jumping out. If that fails, back off and let the pros show up with a foam truck.
Glad you are flying again though... lessons learned.
 
About five years ago I was helping a friend work on a F8F Bearcat. It caught on fire and literally there were flames all the way back to the cockpit. Fortunately he KEPT ON CRANKING and prevented the loss of a priceless airplane.
 
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