Engine quit during takeoff when full throttle applied

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Narwhal

Pre-takeoff checklist
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Hello,

I was doing a series of touch and goes in a C182 with an O-470.

After the 3rd landing, I retracted flaps to 20, turned off carb heat, opened cowl flaps and applied full throttle as I normally would. Instead of the usual increase in RPM, the engine began to quit. RPM's decreased to about ~500 while still on the ground. I pulled the throttle back toward idle, and the RPM came came back to about 1000. I decided to taxi clear of the runway and troubleshoot.

Weather was
092056Z AUTO 23003KT 10SM OVC095 M04/M05 A2984 RMK AO2 SNB02E12 SLP112 P0000 60000 T10391050

Basically 23 F with 90% humidity (70 feet MSL).

Do you think this was carb ice?

I was using full carb heat from downwind to landing.

I pulled off the runway, did a 2000 RPM runup with full carb heat and the mixture leaned (any higher RPM and the brakes wouldn't keep the airplane stationary on the icy taxiways). Everything seemed fine so I did another takeoff and things seemed normal. Carb temp was showing about 50 degrees F during the runup, unfortunately I didn't see what it was showing when it lost power.

Thanks!
 
Don’t know the answer to your question but wow . Few seconds later and it would have been very interesting to say the least
 
Narwhal said:
After the 3rd landing, I retracted flaps to 20, turned off carb heat, opened cowl flaps and applied full throttle as I normally would. Instead of the usual increase in RPM, the engine began to quit. RPM's decreased to about ~500 while still on the ground. I pulled the throttle back toward idle, and the RPM came came back to about 1000. I decided to taxi clear of the runway and troubleshoot.
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You did the right thing!

What was your mixture setting?

The symptom almost sounds like when you try and taxi but the mixture is too lean so when you advance the throttle the engine begins to die..

Odd
 
Tantalum said:
You did the right thing!

What was your mixture setting?

The symptom almost sounds like when you try and taxi but the mixture is too lean so when you advance the throttle the engine begins to die..

Odd
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Mixture was full rich.
 
Very peculiar.. unfortunately these things are hard to replicate so difficult if not impossible to figure out the root cause
 
Does the O-470 have a throttle position sensor? I just went though this. Replaced my TPS today. I think the problem is solved.
 
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Flocker said:
Does the O-470 have a throttle position sensor? I just went though this. Replaced my TPS today. Problem solved.
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You replace a TPS in an aircraft engine, or your car?
 
Too cold. My vote is probably not. Those environmentals are on the light risk, given how little moisture there is. 90% of a small number is a small number.
upload_2020-12-9_18-38-29.png

Induction on a 7:1-jugged O-470 is a basket case on a good day. My random guess is there's something going on with the mixture control et al. I don't think icing did that to ya, and that's saying a lot considering these are ice makers compared to the rest of the pack.
 
SOP is to open the throttle first, then turn the heat off. The heat helps with vaporization of the fuel from the accelerator pump on the carb. And that pump might not be working right, or not set properly.
 
I fly a similar setup, I would suggest carb ice.
I’ve had carb ice on take off on many occasions. We don’t often have high humidity here, but when we do, I’m ready for ice on take off. It is not just me either, many others with similar planes have the same issue.
 
hindsight2020 said:
Too cold. My vote is probably not. Those environmentals are on the light risk, given how little moisture there is. 90% of a small number is a small number.
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Some carb ice charts might be specific to certain aircraft models. They vary somewhat. Here's a different one that says the OP's conditions are fairly serious:

upload_2020-12-9_19-8-31.jpeg
 
Narwhal said:
Weather was
092056Z AUTO 23003KT 10SM OVC095 M04/M05 A2984 RMK AO2 SNB02E12 SLP112 P0000 60000 T10391050

Basically 23 F with 90% humidity (70 feet MSL).

Do you think this was carb ice?

Thanks!
Click to expand...
Do you have a carb ice gauge? if not, why not?
 
23° and 90% RH means there's frozen moisture in the air. Carb heat can warm it just enough to melt the frozen moisture so it can refreeze inside the carburetor.
 
Dana said:
23° and 90% RH means there's frozen moisture in the air. Carb heat can warm it just enough to melt the frozen moisture so it can refreeze inside the carburetor.
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Moisture can commonly exist as liquid down to -20C. It's called supercooled water and it's a hazard in IFR flight (airframe icing) and to carburetors. The carb ice probability charts reflect this. From https://www.boldmethod.com/learn-to-fly/aircraft-systems/dont-let-carb-ice-happen-to-you/ we read:

The temperature range where carb ice can occur is equally surprising. According to the FAA, carb ice is possible from 10F to over 100F, with serious icing possible from 20F to over 90F (-7C to 32C).

Some stuff on supercooling: https://en.wikipedia.org/wiki/Supercooling
 
The fact still is, the gauge says the surface of the carb was 50 degrees. Nothing will stick to the carb at that temp. If nothing is sticking to the carb, any water will simply pass.
 
Tom-D said:
The fact still is, the gauge says the surface of the carb was 50 degrees. Nothing will stick to the carb at that temp. If nothing is sticking to the carb, any water will simply pass.
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But that was on downwind with carb heat on. This occurred after landing and after carb heat was turned off.

How long after carb heat is turned off will the temp in the carb lower?
 
donjohnston said:
But that was on downwind with carb heat on. This occurred after landing and after carb heat was turned off.

How long after carb heat is turned off will the temp in the carb lower?
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was the carb temp 50 or not?
 
Tom-D said:
was the carb temp 50 or not?
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Not at the time he had carb ice.


Narwhal said:
Carb temp was in the green, about 50 F on downwind after I turned carb heat on.
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Narwhal said:
I do not know for certain what the carb temperature gauge was reading on base and final after power was pulled to a low setting, as I perhaps was not paying attention to it as much as I should after initial carb heat application on downwind.
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hindsight2020 said:
Too cold. My vote is probably not. Those environmentals are on the light risk, given how little moisture there is. 90% of a small number is a small number. ...
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If you look at the chart you posted you will see there is not much distance between low risk and high risk at the temp and humidity stated by the OP. The risk rings approach each other in the lower left of the chart.

If the actual OAT was just a few degrees higher than the stated 23F, say 27F, and the actual RH was closer to 95% rather than the stated 90%, the risk rises into the high risk region.
 
I'd venture a guess that the op learned a valuable lesson on keeping the carb warm.

The 0-470 has a remote mounted carb. It does not have the benefit of mounted sump to pass heat from the hot oil.
 
I've seen carb ice temp gauges that were way off. Flew two airplanes that had such problems. The OP should see what it says when he comes out to the airport to fly, before he starts up or preheats the engine. The gauge should read pretty close to what the OAT says.
 
Unless you find a problem with the mixture, and if you are unable to reproduce the problem, I would hazard a guess that you encountered carb icing, carb heat gauge notwithstanding. The reported temp/dew point is within the expected conditions where carb icing could be encountered. The only other thing I could think of is some sort of restriction in fuel flow (ice crystals in the fuel line?) that would result in a overly lean mixture when the throttle is opened and fuel flow is unable to keep up. I had a strange non-reproducible power failure like this during an IPC in sub-freezing conditions and visible moisture. We concluded either carb icing or ice crystals in the fuel lines or fuel pump. I hate it when something potentially catastrophic happens and you can't reproduce it or positively identify the cause.
 
Wagondriver said:
I fly a similar setup, I would suggest carb ice.
I’ve had carb ice on take off on many occasions. We don’t often have high humidity here, but when we do, I’m ready for ice on take off. It is not just me either, many others with similar planes have the same issue.
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I don't think carb ice is likely, because power increased when the OP closed the throttle — that should have made it worse.
 
Sometimes the engine will just quit if you open the throttle too rapidly. Two seconds from closed-to-open is normal. Slamming it open is asking for some hesitation, at least, and can induce brief detonation in some engines. Cold air makes hesitation more likely.

Cylinder pressures can get pretty high at low RPM and full throttle, and the spark can blow out if the mags are weak or the plugs are bad. At higher RPM the magneto is generating a lot more voltage and things are fine.
 
I’ve seen something like this occur with runups withe cowling OFF.

As TomD mentioned the O-470 has a Carb well to the rear of the engine.

The Induction System does not pass through the Sump but relies on warm air

passing down over the cylinders to keep Intake Pipes warm.

If this does not happen ( cowling OFF?) fuel will fall out of suspension with

the air and pool in the Intake System.

This presents as Power Loss and running on at ICO as the pooled fuel

evaporates.

Cold OAT exacerbates the condition and Carb Heat alleviates it.


Not sure how this would happen in flight though.

Temperature of Carb Heat Air is reduced with lower power setting during

approach as is CHT.

Overly Rich Idle Mixture could contribute.

Doesn’t seem like folks “ clear “ the engine after initial power reduction anymore.
 
donjohnston said:
Obviously it was. He stated that in post 14.

What's your point?
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I don’t think it is obvious, he also stated that was carb temp on downwind, that he didn’t know what it was after landing.
Carb is 50 on downwind, power is pulled and the exhaust gets cold quickly with temps in the low 20’s. Everything inside the cowl cools off, cylinders, exhaust, and carburetor. Could very well be that ice was building up all the way down to landing, but not enough to to choke it. With humidity that high, even at those temps, I’d run a lot of carb heat prior to take off to get the carb warmed up, and might even run just enough to keep the carb temp above freezing during take off.
Last weekend I was descending from 12,000 down to about 6500. Cowl flaps closed, 12” and 2300rpm. Up to my descent I was toasty warm, and oil temp was normal at about 189. By the time I got to 6500 feet, my heater wasn’t heating much, and my oil temp after the cooler was down to 107. It took several minutes of 18” and 2300, cowl flaps closed to get the oil temp to even move or to get the heater really working. Down low it was 25 degrees colder than it was at 12000.
 
I don’t understand why you guys think it’s carb icing when he had carb heat on until he began the takeoff.
 
Wagondriver said:
I don’t think it is obvious
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The OP wrote "Carb temp was in the green, about 50 F on downwind after I turned carb heat on."

Tom implied it wasn't carb ice.

Since the carb temp was 50F on downwind but this event happened after landing and turning off carb heat, I questioned how long would it take for the carb temp to cool so that ice could form after turning off the carb heat.

Tom asked "was the carb temp 50 or not?"

Since the OP already answered that question, I think it's pretty obvious that the carb temp was 50F.
 
donjohnston said:
"Tom implied it wasn't carb ice.
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When I wrote that I understood he already had the carb at 50 degrees.

Why would anyone allow the carb to freeze again?

Just remember, there a multitude of aircraft in the junk yards, because pilots don't understand how to use carb air.
 
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Tom-D said:
When I wrote that I understood he already had the carb at 50 degrees.

Why would anyone allow the carb to freeze again?

Just remember, there a multitude of aircraft in the junk yards, because pilots don't understand how to use carb air.
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Now you're saying that a carb was freezing at 50 degrees, thawed and then re-froze?

This would be so much easier if you could just answer a simple question instead of diverting by asking irrelevant questions.
 
Might be interesting now just to check what typical carb temp is at a few points in the pattern typically. That might help give you an idea how different the temp typically is on roll out vs just as ya entered downwind. Just an idea.

Ice is always on my mind.

I fly a known ice maker- the tiny lil sis to the engine here, but same icy tendencies, the c85. My old POH calls for carb heat in right after you start the engine until take off. I do my carb heat check by looking for a rise in rpm turning it off momentarily. It goes off as I take the runway.

I pull my carb heat as I get to the pattern- give it some time before the big rpm reductions...

I put the ntsb reports in excel for the c120/140 and many many had power loss after take off and engine ran fine post crash. Something tells me that though not proven ice is likely the culprit there at least a chunk of the time... so I’ve on TO roll very possible...
 
“Carb Air 50 F on downwind” .

Likely about Cruise Power.

Then power was reduced .

The reduction in power would allow the heat source ( exhaust system)

to cool down and possibly become ineffective.

The procedure of” clearing “ the engine periodically by brief power increases

would have kept exhaust hot.

If this particular approach was made with an extended period of

fully closed Throttle (.too high? ) you may have had little Heat Available.

The fully closed Throttle also causes a pressure drop in Carb

which also gives a Temp Drop.

Could it be that on previous approaches you adjusted power periodically

which provided more effective Carb Heat?
 
donjohnston said:
The OP wrote "Carb temp was in the green, about 50 F on downwind after I turned carb heat on."
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I didn't see that he said 50° on downwind with the heat on, (he said in the runup, I saw) but if it's true, there a problem with his carb heat. Current regulations require a 90° rise in induction air with carb heat on and cruise power. Old regulations might have been milder, or nonexistent, but my experience with the O-470 in a Cessna was that it had so much carb heat that I had to lean the engine on downwind because it got so rich with the heat on.

That system needs a good inspection. Now.
 
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