Killing engine in flight

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Calculatedpilot83

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Curious if it’s a horrible idea to turn off the engine on Cessna 172 to enjoy some quiet gliding on a high altitude decent day 10,000ft to sea level.

Will the engine continue to windmill at glide speed or will it require the starter to restart.

If engine does wind mill will some amount of fuel ( idle amount) still be drawn through carb? If so is there a chance of icing or flooding the engine.
 
When I inadvertently pulled the fuel shutoff knob on Cessna 162 instead of the cabin heat knob, the engine continued to windmill. I thought it was a partial power loss until the prop stopped during rollout after the forced landing (which was fortunately on a runway).
 
I am not sure why you would purposefully create an inflight engine failure. If you want to go gliding, go do some flights in a glider.
 
Calculatedpilot83 said:
Curious if it’s a horrible idea to turn off the engine on Cessna 172 to enjoy some quiet gliding on a high altitude decent day 10,000ft to sea level.

Will the engine continue to windmill at glide speed or will it require the starter to restart.

If engine does wind mill will some amount of fuel ( idle amount) still be drawn through carb? If so is there a chance of icing or flooding the engine.
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If the prop windmills, you may be able to stop it by flying slower until it stops windmilling. I've done intentional glider flights in my RV-6 and find I need to be under 70 knots for the windmilling to stop, but to get it to begin windmilling again requires something like 140 knots. If you pull the mixture to cut-off/all the way to lean, you won't have to worry about any fuel going through the carb. But you will need to richen the mixture for a restart, whether we're talking a windmilling restart or a restart using the starter.

Whether you want to play glider pilot and how you set up the experiment is up to you. If you choose to play glider pilot, think through it and don't do anything dumb.
 
Most pilots would consider it to be not such a great idea.
The prop will continue to windmill.
I would assume there is a potential to foul the plugs as you pull a little oil through the cylinders. Perhaps not a big potential, but a potential.
Unless you have an airport underneath, you are counting on the engine restarting.

Overall, I would rate the risk/reward ratio as being a bit higher than necessary.

Others may disagree
 
IMO it's never a good idea to intentionally kill the engine when in flight. even practicing power-off stalls or 180s downwind-to-final the engine is running.
 
kyleb said:
Whether you want to play glider pilot and how you set up the experiment is up to you. If you choose to play glider pilot, think through it and don't do anything dumb.
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I find those words amusing as my instructor had that exact quote on the panel of his training airplane, "Don't do anything dumb!" When I first spotted it I thought for a moment to ask about it but then concluded that doing that would be dumb. ;)

As for shutting off the engine in flight, go fly a few two stroke light sport type planes. With enough time you'll get a bit of practice at the engine finishing the flight before you do ... :biggrin:
 
SkyChaser said:
I am not sure why you would purposefully create an inflight engine failure. If you want to go gliding, go do some flights in a glider.
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If you turn your strobe lights off do you call it a strobe light failure? Thought it might be good training to see what it takes to get the windmill started again with increased airspeed. Let’s face it, training isn’t risk free. Spins, stalls, forced landings are all more risky than a mindless pleasure flight but we practice them all the time to stay sharp.
 
You wouldn't be the first. Not sure just how much you'll really learn from it, though. You'd learn more from doing power off 180s in various configurations and altitude and wind scenarios. Aside from running a fuel tank dry and maybe carb ice, there aren't too many times when an engine dies that you're going to get it restarted successfully.
 
Maybe everything will go fine.

Just in case it doesn’t, why don‘t we get the ntsb pilot statement drafted now? Nice to have that ready, you know.
Lots of good folk here will help.
Also, near the bottom of every insurance application I do each year, there is a handy place for a narrative where I can explain any accidents, incidents, or claims - we could also start writing that up for you now too, just in case it doesn’t go how you think it should.
Maybe also take a minute to think about other consequences - careless contributions to the GA accident rate affects us all - the FAA is looking at all our goofups thinking of new ways to regulate us; insurance premiums for all of us rise with every increase in accident rates; if you end up in the news, more anti-GA sentiment. Let’s hope you don’t hurt yourself or an innocent person, or damage the plane or someone’s property. How will your friends, family, airport buds look at you once they learn the cause? Is anyone ever going to want to ride with you again?

Maybe everything will go fine.
 
Let'sgoflying! said:
Maybe everything will go fine.

Just in case it doesn’t, why don‘t we get the ntsb pilot statement drafted now? Nice to have that ready, you know.
Lots of good folk here will help.
Also, near the bottom of every insurance application I do each year, there is a handy place for a narrative where I can explain any accidents, incidents, or claims - we could also start writing that up for you now too, just in case it doesn’t go how you think it should.
Maybe also take a minute to think about other consequences - careless contributions to the GA accident rate affects us all - the FAA is looking at all our goofups thinking of new ways to regulate us; insurance premiums for all of us rise with every increase in accident rates; if you end up in the news, more anti-GA sentiment. Let’s hope you don’t hurt yourself or an innocent person, or damage the plane or someone’s property. How will your friends, family, airport buds look at you once they learn the cause? Is anyone ever going to want to ride with you again?

Maybe everything will go fine.
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Omg man. I’m on here asking for advice and leaning on others knowledge, you’re just being a jerk. Unlike the 90% of the other ppl who replied respectfully.

Have you ever practiced a forced landing? Stall? Spin? As pilots we do things that are inherently risky.
 
I’ve heard that whether the engine is windmilling or stopped it’s pretty similar, no idea how accurate that is.

Also I have read that you should give the engine some short bursts of power while doing power off / gliding to avoid shock cooling the engine.

There are different ways to start the engine, whether it’s a cold start, hot start, etc. So you’ll want to have all of those procedures memorized and mastered.
 
airplanes like the 172 are pretty noisy inside, even when the engine stops. Too much drag, lots of whistling. Doubt you’d get the effect you’d want.

Trevor Jacob had to work pretty hard to get his prop to stop windmilling. that was for dramatic effect For his vid. You making a vid?
 
Just be aware that even in “motorglider” (which are designed to stop and then restart the engine later) there are numerous crash/incident reports where the engine would not restart, for various reasons. Motorglider pilots are supposed to not rely on the engine starting and be prepared to make an out-landing (off field landing) just like a non-engine glider pilot.
 
I’ve intentionally shut down an engine once. I felt it was important to know just how much difference there is in an idle engine vs shut down. I got a lot of crap here for doing it. I did it directly above a runway. I still think it was worth the risk to do it once, but I don’t feel the need to ever do it again, and I wouldn’t treat a 172 like a glider.

Here’s the thread if you want to read. https://www.pilotsofamerica.com/com...dmilling-the-truth.132499/page-2#post-3133239
 
Calculatedpilot83 said:
If you turn your strobe lights off do you call it a strobe light failure? Thought it might be good training to see what it takes to get the windmill started again with increased airspeed. Let’s face it, training isn’t risk free. Spins, stalls, forced landings are all more risky than a mindless pleasure flight but we practice them all the time to stay sharp.
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If there was a decent chance they wouldn't come back on if I shut them off? I would saying that was "creating a strobe light failure".

Some airplanes are easy to start on first attempt, even on hot starts. Others aren't. If you're attempting a hot start on the ground, it's no big deal if the engine doesn't "catch" the first time you attempt a start. It is a BIG deal in the air, when you have zero options beside an off-airport landing if that engine doesn't do exactly what you want it to do.

I never said that flying was risk free. However, the whole point of training is to train pilots-to-be how to make good judgments on those risks. Deciding to create an in-flight emergency state is not my idea of good judgment, especially not when the stated reason for the question when I replied was "I want to enjoy some quiet gliding from 10,000ft". Even for training purposes, it has very limited knowledge to be gained and is still on the "great risk with little reward" side of the matrix, especially without a planned and executable exit from such state in case the engine decides not to restart.
 
Op is trolling. Shutting down a single engine is pretty dumb imo, just think about explaining to the FAA if it doesn’t go well. A good pilot realizes a stupid action before he does it, then doesn’t do it.
 
Calculatedpilot83 said:
If you turn your strobe lights off do you call it a strobe light failure? Thought it might be good training to see what it takes to get the windmill started again with increased airspeed. Let’s face it, training isn’t risk free. Spins, stalls, forced landings are all more risky than a mindless pleasure flight but we practice them all the time to stay sharp.
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Don’t try to pass this off as “training.” At best, it’s satisfying your curiosity. It’s very possibly a demonstration of hazardous attitudes.
 
Calculatedpilot83 said:
Omg man. I’m on here asking for advice and leaning on others knowledge, you’re just being a jerk. Unlike the 90% of the other ppl who replied respectfully
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To be fair, I thought it was a reasonable ask until you talked about gliding from 10,000 ft to sea level. That part set off the troll detector for me.

I’ve done it probably twice. I went up to about 7,000 AGL over a ranch strip, pulled it back to idle, then pulled back the mixture. I was surprised by how much of a non-event it was and that the noise wasn’t very different. It also gave me a chance to learn what my real best-glide speed and descent rate was (about 1000fpm in my Warrior and the speed was kind of a band between about 65 and 80 - not a lot of difference at the book 73).

I don’t recall when windmilling stopped and started but it was pretty slow to stop and came back pretty quickly, as I recall.
 
Calculatedpilot83 said:
….If engine does wind mill will some amount of fuel ( idle amount) still be drawn through carb? If so is there a chance of icing or flooding the engine.
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How do you propose to turn the engine off? That should give you an idea of what systems are involved in fuel flow when it comes to fuel being drawn. Same thought process should be applied to carb ice. How does carb ice form? Are those conditions applicable when the engine is not running? What about forced air during the glide?

Attempting restart, how do you prevent flooding to begin with? I think you should be thinking about how long the engine will be off for during the glide and whether or not you’ve practices a restart under similar conditions before.

When you can answer those questions, I think you’ll be in a better place to understand whether or not this is something you want to attempt.
 
Calculatedpilot83 said:
…Have you ever practiced a forced landing? Stall? Spin?
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If you’ve done the things above,
As pilots we do things that are inherently risky.
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You should probably understand why *most* pilots don’t consider an in-flight elective shutdown in a single engine plane to be entirely different from two maneuvers that are are on the check ride and a third that every CFI as part of the required aeronautical experience to obtain their certificate. Many other pilots receive training from a CFI for that third maneuver as well, although I don’t know many who do it on their own without any instruction prior to executing it for the first time.
 
TCABM said:
How do you propose to turn the engine off? That should give you an idea of what systems are involved in fuel flow when it comes to fuel being drawn. Same thought process should be applied to carb ice. How does carb ice form? Are those conditions applicable when the engine is not running? What about forced air during the glide?

Attempting restart, how do you prevent flooding to begin with? I think you should be thinking about how long the engine will be off for during the glide and whether or not you’ve practices a restart under similar conditions before.

When you can answer those questions, I think you’ll be in a better place to understand whether or not this is something you want to attempt.
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In this entire scenario, definitely only turn it off by killing the mags. Leave the fuel flow where it is. Especially if it's a rental.
 
Llewtrah381 said:
To be fair, I thought it was a reasonable ask until you talked about gliding from 10,000 ft to sea level. That part set off the troll detector for me.

I’ve done it probably twice. I went up to about 7,000 AGL over a ranch strip, pulled it back to idle, then pulled back the mixture. I was surprised by how much of a non-event it was and that the noise wasn’t very different. It also gave me a chance to learn what my real best-glide speed and descent rate was (about 1000fpm in my Warrior and the speed was kind of a band between about 65 and 80 - not a lot of difference at the book 73).

I don’t recall when windmilling stopped and started but it was pretty slow to stop and came back pretty quickly, as I recall.
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Thanks for the info, I’m not trolling, just a new pilot asking questions and gaining knowledge. Where I fly all the airstrips are very close to sea level.
 
I have to chuckle when people freak out about intentionally shutting off an engine. Between glider ratings and the requirement to shut down an engine in both training and the check ride for multi engine rating, I'm always amazed at how irrational people are about this topic. The odds of the engine not restarting are just not that high.

Again, I'm not a proponent of doing what the OP suggested, but I don't think it's irresponsible to fly without an engine under the right circumstances.
 
Salty said:
I have to chuckle when people freak out about intentionally shutting off an engine. Between glider ratings and the requirement to shut down an engine in both training and the check ride for multi engine rating, I'm always amazed at how irrational people are about this topic. The odds of the engine not restarting are just not that high.

Again, I'm not a proponent of doing what the OP suggested, but I don't think it's irresponsible to fly without an engine under the right circumstances.
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Yeah, my very first CFI would do surprise engine failures by killing fuel via the fuel selector. Engine always came back when reintroducing fuel, and more importantly it did a good job of teaching startle effect of when you truly aren't expecting it. It has value, it was done in a safe manner. Engines aren't magic, remove fuel they stop, reintroduce fuel they go.
 
Gilbert Buettner said:
Losing engine power in flight is an emergency. I don't intentionally create emergencies.
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While I get your point, it’s equally fair to say a partial loss of power (down to idle power) is also an emergency yet we practice that often.

I personally think there’s merit in doing this, under the right circumstances. For example, it seems good for a CFI to intentionally do it once with a student, planned, at altitude and near a good runway, to show them early on that the plane won’t fall out of the sky if the engine quits; it would better prepare them for such a situation by reducing the panic, IMHO. I could also see doing it with a spouse (if they’re willing!) for the same reason.

And while others have talked about shutting off a fuel valve, I personally hesitate to do that. That introduces another variable/failure mode that doesn’t add benefit, in my opinion.

Also, I personally pull it to idle first. I’m sure it’s probably safe to pull the mixture back while at full power but I just don’t want to add stress to the engine. That said, I could imagine it’s a good lesson to see how the plane behaves going from full power to nothing in a heartbeat. I just opt not to do that.

I’ve also done it just with the mixture: turning the ignition off is not wise, in my mind, for several reasons: a new failure mode and raw gas getting into the exhaust being the main two.
 
When I learned to fly in the early 1970s, the instructors would kill the engine for a simulated failure by pulling the mixture. That introduces the possibility of plug fouling or a mixture control cable failure, but it removed much of the carb ice risk. A large part of of the refrigeration in the carb comes from evaporating fuel; the rest is from the pressure drops in the venturi or throttle plate/carb throat gap, depending on throttle position. Turning off the mags for a long glide is just asking for carb ice. There is no exhaust heat to prevent it, and once it has formed and clogged the carb, you're hooped. You have no heat to remove it.

If the prop isn't stopped, there is little noise difference between idle power and no power. In about 1976 I was getting checked out in the 150, and the instructor pulled the mixture to see what I would do. I picked a field and set it all up ok and he pushed the mix back in and we climbed back up. I asked him how slow we'd have to get to stop the prop, and he said, "Dunno. Let's try." So we did. We were on the edge of the stall when it finally stopped. We glided a bit, then I dove to see if we could get it restarted. Up to Vne and it would not flick over. Bumped the starter and away it went.

And that points out another factor: a starter that has decided to stay quiet. Lycoming-type starters are famous for sticking starter drives, and a long, cooling glide could bring that on. Mechanics love to spritz that drive with oil, which attracts dust and creates a sludge that gets sticky and stiff and hampers the drive engagement. I wish they'd read the manuals.
 
"we do it in training, so why not do it to get that noisemaker up front to finally shut up" seems like a really odd comparison. "Trying to teach a lesson" vs "Trying to not harsh my spotify jams" don't seem like equivalent causes.
 
Calculatedpilot83 said:
Curious if it’s a horrible idea to turn off the engine on Cessna 172 to enjoy some quiet gliding on a high altitude decent day 10,000ft to sea level.

Will the engine continue to windmill at glide speed or will it require the starter to restart.

If engine does wind mill will some amount of fuel ( idle amount) still be drawn through carb? If so is there a chance of icing or flooding the engine.
Click to expand...
I had a great deal of anxiety about leaning the mixture in flight because I was afraid the engine would quit, but then I did a BFR with a CFI who showed me that you can kill the engine entirely by leaning to full lean but as soon as you push it back full rich, the engine roars back to life. Granted, that's not what you're asking to do exactly but it implies that the risk is ow as long as the prop is windmilling
 
Dan Thomas said:
would kill the engine for a simulated failure by pulling the mixture. That introduces the possibility of plug fouling or a mixture control cable failure,
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Honest question: while I agree with the mixture cable failure possibly (which is also a possibility if one leans heavily while at altitude), how would doing that raise the risk of plug failure? Seems like they’re still firing despite there being nothing to burn, so that risk doesn’t seem increased. That’s one reason I don’t think turning the mag off is wise - that and, when the spark does resume, the raw gas then getting lit in the exhaust can cause “backfiring”.
 
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