Remember to make your mags "cold"

Why I say do not pull the mixture lean to shut your engine off. Shut the fuel flow off to the carb and let her die. Once she dies then pull mixture to lean and shut her down or turn off the mags. Now you have an unloaded engine. How I kill my engine every time I am done flying. Now if someone does walk up and start pulling on the prop or move it, even if the mag is left hot it will not start. Nor will you ever take off with the fuel shut off. It can not happen for the only way to start the engine is to turn the fuel flow on. You can push the mixture fuel rich and she will never start. Not until you open the fuel valve.
 
How often does your plane start on it's own?......that sounds like a problem.:yikes:

Full disclosure......in +30's of flying I've never seen one start on it's own....most times they start reluctantly. :mad2:
 
You always leave a gun empty...
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No.

My truck gun is loaded right this very minute. So are other firearms I keep but will not go into details on a public forum.
 
flhrci said:
Brain fart is what I think happened.
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Triple Brain Fart. First was leaving the mags on, second was not checking the mag switch(es) before pulling the prop, and third was expecting that the engine wouldn't fire and thus exposing himself to injury when it did.
 
flhrci said:
Our airport's A&P forgot to shutoff the mag switches in a Citrabia today and he left the spark plug wires attached to the engine. David
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I've never seen any one detach the plug wires when they shut down.
 
An unloaded gun makes a very poor club.
 
RobertSubnet said:
No.

My truck gun is loaded right this very minute. .
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So are mine, and it is no ones business when they aren't.
When the G/kids come they are in the safe.

Gun responsibility. is what is not taught to the general media.
 
Tom-D said:
When the G/kids come they are in the safe.
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oops,, I don't put the G/kids in the safe, to keep them from getting to the loaded guns, :)
 
Very eye opening thread for anyone following along. It really does show what some of the members here are made of.
 
1600vw said:
Why I say do not pull the mixture lean to shut your engine off. Shut the fuel flow off to the carb and let her die. Once she dies then pull mixture to lean and shut her down or turn off the mags. Now you have an unloaded engine. How I kill my engine every time I am done flying. Now if someone does walk up and start pulling on the prop or move it, even if the mag is left hot it will not start. Nor will you ever take off with the fuel shut off. It can not happen for the only way to start the engine is to turn the fuel flow on. You can push the mixture fuel rich and she will never start. Not until you open the fuel valve.
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Even with this procedure, it won't run, but it can leave enough residual fuel in the system to fire once or twice. I've seen it happen.
 
flyingron said:
Even with this procedure, it won't run, but it can leave enough residual fuel in the system to fire once or twice. I've seen it happen.
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If you let the engine die or run out of fuel it will not fire again. No way. No residual fuel will be left behind.

No matter what you say this is the best way to shut down your engine.

Tony
 
1600vw said:
If you let the engine die or run out of fuel it will not fire again. No way.
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True, in most cases*.

And a gun without a round in the chamber cannot fire. No way.

I would still hold that the best safety practice is to assume they both are "loaded".


*Combine gravity feed with a leaky carb and a shutoff valve that's not closing 100%, and fuel could still find its way back into a cylinder.
 
FastEddieB said:
True, in most cases*.

And a gun without a round in the chamber cannot fire. No way.

I would still hold that the best safety practice is to assume they both are "loaded".


*Combine gravity feed with a leaky carb and a shutoff valve that's not closing 100%, and fuel could still find its way back into a cylinder.
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No the best practices is to unload both the gun and the engine, then treat both as they are loaded.

Don't walk away from a loaded engine. Unload your engine as you would a firearm. Simple and safe for anyone who might happen to walk up and touch said engine or prop.

I have always wondered why this was not taught as good practice. Not only can it help save someone walking it also stops all takeoffs with the fuel valve left off. No way you will ever start your engine if you do not first turn on the fuel. It won't even fire.

I do this in both my Gravity feed airplanes. With Ball cocks like we use they do not leak. Why they are used in aviation. But if one does leak using this method you would know it. Using any other practice you will never know if this ball cock or shutoff valve was leaking. How would you?

Try it.

Tony
 
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As an aside, ROTAX 4-strokes are normally killed by turning off the ignitions. They do not have mixture controls*. Hence the float bowls stay full and the engine is definitely "primed" and ready to start if the ignition is left on or a "p-lead" is faulty.

One difference is the geared engine - turning the prop results in much less crank movement - something like 2.2:1 IIRC.

Once a year I turn off my fuel shut-off valve - its part of the annual condition inspection. Its always worked, and I suppose I could shut down that way as a matter of course. Only drawback I can see is the engine gets very rough for a few seconds as one Bing goes dry right before the other.


*As delivered. They can be retrofitted from a third party.
 
I hear that some planes have a redundancy in the ignition system that makes it so if there is a broken wire on the mags it makes their circuit live at all times (my instructor said so about the cessna 150 we use) as a professional automotive mechanic I can say, in such a situation, anytime you bring the engine to top dead center there is an opportunity for the engine to start. also fuel can self ignite under compression. its probably unlikely with avgas but diesel engines work on this principal and I have personally seen gasoline engines run without spark when they are rich enough. even from my limited student pilot perspective it just seems best to be prepared for the possibility of the engine starting anytime you even touch the propeller. why chance it?
 
kyle17428 said:
I hear that some planes have a redundancy in the ignition system that makes it so if there is a broken wire on the mags it makes their circuit live at all times (my instructor said so about the cessna 150 we use)
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It's not a "redundancy" it's how a magneto works, you have to ground the points to get it to stop.
 
kyle17428 said:
I hear that some planes have a redundancy in the ignition system that makes it so if there is a broken wire on the mags it makes their circuit live at all times (my instructor said so about the cessna 150 we use) as a professional automotive mechanic I can say, in such a situation, anytime you bring the engine to top dead center there is an opportunity for the engine to start. also fuel can self ignite under compression. its probably unlikely with avgas but diesel engines work on this principal and I have personally seen gasoline engines run without spark when they are rich enough. even from my limited student pilot perspective it just seems best to be prepared for the possibility of the engine starting anytime you even touch the propeller. why chance it?
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It had nothing to do with the mixture being to rich or rich enough to make a gasoline engine diesel or run on after shut down. What is causing this is carbon build up and getting hot. This carbon will then start to get so hot it will glow red hot. When this happens you have a condition that is called run on. When you shut the key off it keeps running. Its because you have removed the spark, but the carbon is still glowing red hot. It takes some time for the fuel to cool this enough for it to stop running. If its bad enough you may not be able to stop said engine, for as it fires the mixture it makes this carbon hot again. You can also hear it for its an uncontrolled burn and you hear the rods and crank knocking. It sounds like someone through a bunch of gravel in the cylinder. The engine is hurting and begging for help.
Run-on has nothing to do with mixture or timing. Its a hot spot caused by carbon.

Tony
 
kyle17428 said:
redundancy isnt the word I guess. its a safety feature.
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It is not a safety feature either. If the P-lead (ground) is broken, it makes the mag "hot" at all times which makes it unsafe to turn the prop by hand. You need to have your CFI explain it to you better.
 
1600vw said:
If you let the engine die or run out of fuel it will not fire again. No way. No residual fuel will be left behind.

No matter what you say this is the best way to shut down your engine.

Tony
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Its not called residual fuel, its called fumes, and all it takes is a spark and one cylinder to fire causing the prop to make one or two turns. The liquid gasoline will not burn but the fumes can and will make an explosive mixture.

It has happened before with fatal results. With mags off and fuel valve turned off.
 
Zeldman said:
Its not called residual fuel, its called fumes, and all it takes is a spark and one cylinder to fire causing the prop to make one or two turns. The liquid gasoline will not burn but the fumes can and will make an explosive mixture.

It has happened before with fatal results. With mags off and fuel valve turned off.
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Turning the fuel valve off does nothing if you did not let the engine die or the carb run dry. You left your engine loaded.

A cold engine takes more then some vapors to get it to run. It takes a very rich mixture. You are not going to start said engine if you have ran the carb dry by letting said engine stop running on it's own. Never will fire the cylinder. Why we have chokes and cold start systems. If the engine would fire on some vapors when cold we would not need these systems. It won't fire.

I will always shut my engine down this way. You do as you please.
 
1600vw said:
Turning the fuel valve off does nothing if you did not let the engine die or the carb run dry. You left your engine loaded.

A cold engine takes more then some vapors to get it to run. It takes a very rich mixture. You are not going to start said engine if you have ran the carb dry by letting said engine stop running on it's own. Never will fire the cylinder. Why we have chokes and cold start systems. If the engine would fire on some vapors when cold we would not need these systems. It won't fire.

I will always shut my engine down this way. You do as you please.
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I agree, turning the shut off valve will do nothing if the carb is left full of fuel. I think that is why some folks say after the carb runs dry after pulling the mixture to idle cut off they then turn the fuel valve off.

I never said the engine would start and run. There could, read again, there could be just enough fumes in the intake or one cylinder after shut down to fire off a cylinder if it somehow receives a spark. The engine will not start and run as if you are planning to fly, maybe one half or one rotation, but that is all it takes to end a life. The engine does not have to be running for the prop to do major damage to someone.

It has happened before with fatal results.

All I am trying to convey to everyone is that shutting off the mixture does not mean there is no fumes left in a cylinder or intake. But shutting off the engine after a flight by the mixture and shut off valve and mags does not ensure that engine does not have any fumes in it and won't fire off one or two cylinders. Now after a day or a week there is a very good chance all the fumes have evaporated away.

I did not mean for this to become a lesson on safety, but folks, understand that fumes can make the engine turn the prop fast enough to kill a person. Pulling the mixture to idle cut off, switching off the mags and turning the fuel valve(s) to off does not ensure that there are no fumes in the engine and does not ensure that one cylinder in the engine will not pop off and turn the prop at a dangerous speed for 1/2 or 1 rotations if somehow a spark sets off the fuel.

As you said, do as you please. The safest thing is to stay away from the prop and direct others away as well. I'll do what is safe.
 
Pulling the mixture to idle cutoff kills the engine because the mixture gets too lean to burn. You need between 8:1 (rich) and 18:1 (lean) air/fuel by weight to get combustion. If the engine dies when you cut the mixture, it's dead enough. You won't get enough fumes from the carb bowl to make any dangerous difference.

But if it's injected, the hot engine will boil fuel out of the injector lines into the intakes after shutdown. Now you have a killer.

You're right, though: treat any props as a big, sharp axe waiting to chop your head off.
 
Zeldman said:
I agree, turning the shut off valve will do nothing if the carb is left full of fuel. I think that is why some folks say after the carb runs dry after pulling the mixture to idle cut off they then turn the fuel valve off.

I never said the engine would start and run. There could, read again, there could be just enough fumes in the intake or one cylinder after shut down to fire off a cylinder if it somehow receives a spark. The engine will not start and run as if you are planning to fly, maybe one half or one rotation, but that is all it takes to end a life. The engine does not have to be running for the prop to do major damage to someone.

It has happened before with fatal results.

All I am trying to convey to everyone is that shutting off the mixture does not mean there is no fumes left in a cylinder or intake. But shutting off the engine after a flight by the mixture and shut off valve and mags does not ensure that engine does not have any fumes in it and won't fire off one or two cylinders. Now after a day or a week there is a very good chance all the fumes have evaporated away.

I did not mean for this to become a lesson on safety, but folks, understand that fumes can make the engine turn the prop fast enough to kill a person. Pulling the mixture to idle cut off, switching off the mags and turning the fuel valve(s) to off does not ensure that there are no fumes in the engine and does not ensure that one cylinder in the engine will not pop off and turn the prop at a dangerous speed for 1/2 or 1 rotations if somehow a spark sets off the fuel.

As you said, do as you please. The safest thing is to stay away from the prop and direct others away as well. I'll do what is safe.
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and this my friends is why.....the Bonanza gets securely locked behind closed doors each and every time we shut down. :goofy::yes:
 
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Pulling the mixture to lean does not empty the carb. The carb still has a full fuel bowl. The only way to empty the carb of fuel is to shut the fuel valve off and let the engine die or run out of fuel. Then pull mixture lean and kill the mags. The only way to really unload your engine.

Engines with fuel injectors do not apply.

Tony
 
There is a question I've always wondered about flying behind a Rotax. Is there something different about the CDI vs a magneto that makes this a less likely issue?

I've always felt a bit gun shy with the burping of the engine for the preflight, but everyone else I've talked to has made it seem like its not an issue with the electronic ignition. I am not sure if this is true or not?
 
aanderson81 said:
There is a question I've always wondered about flying behind a Rotax. Is there something different about the CDI vs a magneto that makes this a less likely issue?
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First, I would still treat a ROTAX engine/prop like a loaded gun.

That said, I believe two factors makes it safer.

1) The gearing makes the engine turn over at just under half the speed of the prop.

2) The magnets that generate the voltage for the CDI have to be spun pretty rapidly to provide spark. Hand propping generally cannot generate that kind of speed.

I think.

That said, when I burp my ROTAX, no part of my body is in the propeller arc, and my grip on the blade is an open cupped hand. These are just good safeguards regardless.
 
FastEddieB said:
1) The gearing makes the engine turn over at just under half the speed of the prop.

2) The magnets that generate the voltage for the CDI have to be spun pretty rapidly to provide spark. Hand propping generally cannot generate that kind of speed.
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Other way around. The engine turns faster than the prop. That's how it makes horsepower from small displacement while still driving an efficient propeller. The prop wouldn't need to move too far or too fast to make a spark, but it would take more effort than a direct-drive.
 
You're right of course. I guess I just had a brain fart* working through backwards from propeller to engine. Thanks!

*Or recurring mature onset dyslexia!
 
Sorry 1600VW, but I guarantee you it *CAN* happen. The engine will stop once there's not sufficient fuel-air mixture for continuous running. That doesn't mean that all the fuel is exhausted from the system. It won't run very long, but there could be indeed be enough in there to fire a cylinder.
 
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