What does happen when the mixture is accidentally pulled?

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Hasan Bahcivan

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HasanBahcivan
Relatively new pilot here. Consider the following hypothetical scenario for a Cessna 172. You are on a 5 mile final and you realized that you are too high and too fast and decided to pull out the throttle, but instead you pulled out the mixture and the engine stopped.

I know that if you notice the engine startling and immediately push the mixture in, it will restart. But, what if you wait too long and everything is silent, just the wind. Will the propeller continue to turn? In what direction?

My guess is as long as the propeller is turning in the right direction, the engine will restart as soon as you push in the mixture. If the propeller is not turning, it won't (without the ignition key).

I would appreciate your responses.
 
As most 172’s are equipped with a vernier style mixture, the chance of ‘accidentally’ pulling it to idle cutoff would be slim, as the operator would have to push in and then pull it out. It works as a safety mechanism for such events as this.

The old style would be much more prone to this.

-That would be a major brain fart if you did that.
 
Push mixture back in. Motor starts effortlessly. Yes, the prop keeps spinning, and since you're still moving forward it turns in the normal direction.

5 mile final? Try it while coming into a short strip while about 100' above the trees. Mixture and carb heat can feel the same but pulling them has very different results!
 
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Ryanb said:
The old style would be much more prone to this.
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Especially in an older airplane, in which the knobs (other than the throttle) are all of the same size and color.

Definitely gets one's attention....
 
The correct answers have been given. Just adding to add mixture slowly/smoothly so if you're operating at high density altitude the engine doesn't flood. This bit of attention to detail is particularly important with turbocharged engines where full rich will be too rich without the boost.
 
Carry a change of underwear in your flight bag


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As a student pilot on a solo cross country in an older 150 I did just that. Put the mixture back in after a few seconds and it started right back up. Still scared the hell out of me. Long story but I had gotten lost on the long leg due to a wind shift from a warm front. Way before GPS was something any of us had heard of. Was a little shook up and I accidently grabbed the mixture instead of the throttle on a long final to Joplin, MO. Great learning experience though.
 
Mizzou93 said:
As a student pilot on a solo cross country in an older 150 I did just that. Put the mixture back in after a few seconds and it started right back up. Still scared the hell out of me. Long story but I had gotten lost on the long leg due to a wind shift from a warm front. Way before GPS was something any of us had heard of. Was a little shook up and I accidently grabbed the mixture instead of the throttle on a long final to Joplin, MO. Great learning experience though.
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Times like that, just reverse the last input that you made. Good job!
 
This happens after the pre landing check??
 
asicer said:
Try it once with the engine idling, then try it with engine off?
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Yeah that would work, but with the engine idling you still have an out if the A/S does not pick up quick enough. Once the engine is off and the plane starts rolling, you are committed no matter what.

After all that, I would still try it....:yesnod:
 
I'll confess, I've done it before. I had recently transitioned to a different make of aircraft and was taking my new girlfriend on a dinner date. Entering the pattern at home I was distracted by other traffic and getting sequenced. I reached for the 'carb heat' lever while looking out the window and was shocked by a massive rpm drop. I immediately shoved the 'carb heat' lever back in and the engine resumed running. I had never really experienced bad carb ice before and couldn't figure out what caused the rpm drop.

So what did this intrepid pilot do...pulled the 'carb heat' lever out again.

This time I realized which knob my hand was on and the lightbulb came on. The levers in this new to me aircraft were reversed from my prior aircraft, and the 'carb heat' lever was the mixture.

Fortunately the engine came right back each time, and even if it didn't I was properly set up on downwind and could have easily made an engine out landing if necessary.

BTW, I later married the girlfriend and are still happily attached.

And she still flies with me.
 
Done it. Hadn't flown for a few months, rented a tired old Cherokee. Took off, and when I leveled off and pulled the throttle... ooops. Wrong knob. It got really quiet. Pushed the mixture back in, eased the throttle back, kept flying. I waited until I had landed to try to pull the seat cushion out of my ass.

It's a non-event, the prop keeps turning, but it will get your attention and make you feel like an idiot.
 
If you were that high you should already have the field made.

But just put the mixture back in and alls well

If you fell asleep and the prop already stopped kick the starter over.


Ether way no biggie
 
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