Three minutes twenty-four seconds.

Shepherd

Shepherd

Final Approach
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Shepherd
That's how long it took to make enough carb ice to kill the engine.
The C-85-8 makes more ice than a refrigerator/freezer. Seriously.
The manual for the C-85-8 says to keep the carb heat on at all times while sitting or taxiing when the conditions will create ice. I know this. I usually practice safe carb heat.
Today, I did my run-up and forgot to leave the carb heat on when I finished.
Add in a "Hold short for landing traffic."
When the tower released me I went out on the runway and started my takeoff roll.
And the engine stopped stone, cold, dead.
Three minutes and twenty-four seconds from run-up to dead engine.
I ended up dragging the plane off the side of the runway.
It restarted on the third pull. <edited for accuracy.
The entire embarrassing episode was caught on camera.
The rest of my 2.2 hour flight today was uneventful.
 
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Wow. I have to say I'm happy it was on the runway, not something you realized when you were trying to climb out and couldn't. Good reminder.

Which airport, if you don't mind sharing?
 
At least it’s a lot harder to mess up an engine failure on the ground. I’d like that part.

So when you take off again soon, does tower think you’re taking a plane airborne with engine problems? Or do you give them a 3 minute dissertation on carb ice?
 
OMG! Bravo for that bit of luck!

Had one shut down on me on roll out once (wasn’t carb ice…), certainly got my attention. Had to do the same drag it off the runway and tell tower they’re about to get a call from my bud! Who drove out and restarted me….
 
Shepherd said:
That's how long it took to make enough carb ice to kill the engine.
The C-85-8 makes more ice than a refrigerator/freezer. Seriously.
The manual for the C-85-8 says to keep the carb heat on at all times while sitting or taxiing when the conditions will create ice. I know this. I usually practice safe carb heat.
Today, I did my run-up and forgot to leave the carb heat on when I finished.
Add in a "Hold short for landing traffic."
When the tower released me I went out on the runway and started my takeoff roll.
And the engine stopped stone, cold, dead.
Three minutes and twenty-four seconds from run-up to dead engine.
I ended up dragging the plane off the side of the runway.
It restarted on the first pull.
The entire embarrassing episode was caught on camera.
The rest of my 2.2 hour flight today was uneventful.
Click to expand...
Any idea on why you forgot?
 
I realize some engines make more ice than others. While I have had an occurrence like yours with my PA28-181 O360A4M, it was after doing low power IFR practice approaches when my engine stumbled on the missed approach with insertion of full power. Fortunately, I was immediately on top of it with carb heat but did not leave it in long enough(should have left it on a minute or more). But the power restoration was enough to let me think all was probably back to normal so I entered the pattern and landed. After the full stop, I proceeded to taxi back, do another run up to 2000 rpm to confirm the engine performance with momentary carb heat. However, when it was time for full power on takeoff the engine was stumbling. I canceled the takeoff, taxied back to my tiedown and parked for the day.

For my usual practice, on the first flight of the day, I just use carb heat on runup really just to check its normal operation, but am always worried of the ingestion of dirt and debris during ground operations, so I use sparingly and judiciously. Never remember operating an engine like the OP’s where ground operations with carb heat were mandatory during likely weather conditions. I would have to guard against my prejudice to not using CH under similar circumstances.
 
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Albany Tom said:
Wow. I have to say I'm happy it was on the runway, not something you realized when you were trying to climb out and couldn't. Good reminder.

Which airport, if you don't mind sharing?
Click to expand...
KPOU. Dutchess County, Hudson Valley Regional,
The airport with the serious identity crisis.
 
sourdough44 said:
At least it’s a lot harder to mess up an engine failure on the ground. I’d like that part.
So when you take off again soon, does tower think you’re taking a plane airborne with engine problems? Or do you give them a 3 minute dissertation on carb ice?
Click to expand...

I identified the problem as carb ice to the tower as soon as it happened. They were going to send someone out to tow me, but I got it started before they could contact anyone.
I have to say the people in the tower exhibited some concern about me proceeding, which was nice.
 
Yes indeed. It's all captured on my GoPro.
I'll post the video when I get a chance to edit it.
 
Identity crisis….

So there I was. Ft Walton Beach turn, MD-80, I’m a first officer. Fed shows to jump seat (read get home). I can’t find my plates… at all… arg… fed jumpseater, gotta fess up and go make copies at the gate house.

Hey boss, can’t find my plates.
“Did ya look under EGLIN AFB?”
D’oh…

Becomes obvious he can’t find them either… Fed chuckles. “You got anything to add here?” asks the Capt

“Ever wonder what VPS stands for?” Ya, meh…

VALPARISO!

Ooooooooh… always wondered where the heck that was! Geesh…

Seriously, THREE names?
 
Shepherd said:
KPOU. Dutchess County, Hudson Valley Regional,
The airport with the serious identity crisis.
Click to expand...


Glad it turned out ok for you.

One of my first longer trips after my PPL checkride. I called in 10 miles out "Poughkeepsie tower with my tail number" I was quickly corrected sir we are Dutchess tower.....
 
I'm glad you didn't get off the ground at 3 minutes and 5 seconds.
 
PaulS said:
I'm glad you didn't get off the ground at 3 minutes and 5 seconds.
Click to expand...

BTDT, was about 3 minutes in a C-150 between carb heat and takeoff. at 400 feet the engine lost 300 RPM and started running Rough. Applied Carb Heat and lost another 200 RPM while turning back to the runway with just enough power to barely maintain altitude. After the 180 turn I had the runway made from anywhere on the downwind so decided to continue downwind a bit so I could make semi normal into the wind landing. About midfield downwind the engine gained 300RPM and all was normal. Took 30-45 seconds for Carb heat to have any effect. Usually I see it fix carb ice within a few seconds but occasionally it takes longer.

Thinking about why carb Ice would cause the engine to die upon application of power. Initially thought moving the throttle plate caused the ice to break loose and be ingested from the engine. But I like my second theory better that ice forms around the throttle plate and when the throttle is opened the block the carburetor throat starving engine of fuel and air.

I don't recall Carb Ice ever killing an engine at WOT without some warning.

Brian
 
brcase said:
BTDT, was about 3 minutes in a C-150 between carb heat and takeoff. at 400 feet the engine lost 300 RPM and started running Rough. Applied Carb Heat and lost another 200 RPM while turning back to the runway with just enough power to barely maintain altitude. After the 180 turn I had the runway made from anywhere on the downwind so decided to continue downwind a bit so I could make semi normal into the wind landing. About midfield downwind the engine gained 300RPM and all was normal. Took 30-45 seconds for Carb heat to have any effect. Usually I see it fix carb ice within a few seconds but occasionally it takes longer.

Thinking about why carb Ice would cause the engine to die upon application of power. Initially thought moving the throttle plate caused the ice to break loose and be ingested from the engine. But I like my second theory better that ice forms around the throttle plate and when the throttle is opened the block the carburetor throat starving engine of fuel and air.

I don't recall Carb Ice ever killing an engine at WOT without some warning.

Brian
Click to expand...

I don't fly a carb ice engine any more, but I still remember one of my first flights as a student, my instructor covered carb ice and heat. He said carb ice sneaks up on you, but once you suspect it, go full carb heat and don't touch it. He told me if you have a lot of ice, heat will make the engine run worse, that's the ice melting and being ingested by the engine. He said people mistake that for making the problem worse, pull the carb heat and lose the engine. The other thing he said is when the engine is running lousy it's not making much heat so it might take a while to clear. Be patient.
 
Was once flying the original Fly Baby (C85) on a very cool day. Had the carb heat on, but a long power-off glide to a landing gave ice the opportunity to form and choke off the engine. It continued to windmill during the approach, giving no signs of trouble until I was rolling out. Then it just quietly...stopped. Managed to roll off onto a turnoff. Like Shep, a couple of flips of the prop and it was running again.

Frank Courtney's "The Eighth Sea" is an account of test flying beginning before the First World War. He describes flying in a cross-country race just after the war when his engine quit. He landed safely, and was looking at the engine when a big chunk of ice dropped out of the carburetor throat....

Ron Wanttaja
 
kgruber said:
I start my take-off roll with full carb heat. Then push it off after a time.
Click to expand...

That's exactly how I usually do it, except for being distracted this time.
My engine maxes out at 2,575 rpm. Carb heat drops it 200ish rpm. I can safely take off with carb heat on and it's only a 75ish feet difference in takeoff distance.
 
We have beaten this subject to death before.

The weather folks publish METARs all the time. Every hour. In those METARS are the current temperature and dewpoint. I'd bet that not one in 50 private pilots ever look at those numbers.

When the temp and dewpoint are close together, expect carb ice. It's not rocket science. There is no reason to get blindsided by carb ice.

For the Fahrenheit folks:

upload_2023-2-14_16-46-52.jpeg

Find 50°F on the bottom line. Find 40°F on the right side. Where the lines from those intersect is what your ice risk will be, depending, of course on the engine and its installation. For the small Continentals, take this stuff seriously. In our case of 50 and 40, the intersection is in the serious icing even in cruise.

For the Celsius folks:

upload_2023-2-14_17-3-39.jpeg

Now, the METAR for some random place like Hamilton, Ontario, Canada:

upload_2023-2-14_16-53-35.png

Temperature is 6°C, dewpoint is 4. Think maybe icing is a problem?

Icing is a bigger problem at idle power. Much bigger. With wide-open throttle, the venturi is causing acceleration of the airflow. It does this to create a pressure drop to suck the fuel from the main nozzle. The laws of physics tell us that if we accelerate air, its pressure falls. Those same laws also tell us that if the pressure falls, so does the temperature. So the air gets colder as it passes through the venturi.

But downstream of the venturi is the throttle plate. Wide open, it's not offering much restriction and the air ignores it. But when we start closing the throttle, that plate gets in the way so as to reduce the volume of air passing it. That squeezes the airflow between the edge of the plate and the wall of the carb, which accelerates it. That makes it even colder than the venturi did. When the throttle is mostly closed, at idle, there's small amount of airflow around the edge of the plate, and its speed is phenomenal. Its pressure at the edge of the plate is really low, so it gets really cold. It's also sucking fuel from the idle fuel ports in the wall of the bore, and so we have evaporative cooling there too, and that carb will ice up real quick even on a hot day, if there's enough moisture in the air to make ice. Look again at the charts and see that icing is possible at over 100°F or over 37°C. Hot days. But you also need lots of humidity, and that will be reflected in the dewpoint. It will be near the temperature.

upload_2023-2-14_17-9-25.jpeg


Shep got caught because he forgot the carb heat. Most pilots get caught because they know too little about carbs and what nasty little refrigerators they are, and because they think a nice clear day presents no ice risk. The stuff they can't see, the water vapor, is waiting to get them.
 

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Its a great video.

Would love to see a follow on video of trying to demonstrate carb ice.

Brian
 
Gilbert Buettner said:
I think you are referring to ATIS. METARS are automated. You are getting the average of the last few minutes.
Click to expand...
Look at that METAR I posted for Hamilton. Hourly, for those three issued. From our Canadian AIM:

METEOROLOGICAL OBSERVATION AND REPORTS 1.2.1 Type and Frequency of Observations METARs are coded weather observations that are taken every hour on the hour at over 200 aerodromes and other locations in Canada. In addition, SPECIs are issued whenever weather conditions cross specified criteria. For details on how to understand METARs, see MET 8.3. For details on SPECI criteria, see MET 8.4.
 
This must be a difference between Canada and the US. US METARS are automated by ASOS and AWOS systems. At towered airports, weather observers update ATIS hourly or more often if weather is changing rapidly.
 
Gilbert Buettner said:
I think you are referring to ATIS. METARS are automated. You are getting the average of the last few minutes.
Click to expand...


IIRC, METARs might or might not be automated. If a METAR is automated, it will say AUTO after the date and time.

https://www.weather.gov/media/wrh/mesowest/metar_decode_key.pdf
upload_2023-2-14_21-9-43.png
​
I'm not sure that I've ever seen a METAR that wasn't automated, but it seems like it's certainly possible.

Come to think of it, though, I've frequently seen METARs that were old or expired, so perhaps those were manual.
 
Smaller airports in Canada that don't have an FSS usually have automatic observations stuff. Major airports have people doing the readings and briefing pilots in person or by phone. Near us is a small, uncontrolled airport:

SWIFT CURRENT/SK (show WxCam)

METAR CYYN 150200Z AUTO 29011KT 9SM CLR M13/M15 A3000 RMK ICE MISG SLP220=
METAR CYYN 150100Z AUTO 31012KT 9SM CLR M13/M15 A2999 RMK ICE MISG SLP216=
SPECI CYYN 150023Z AUTO 31011KT 9SM CLR M13/M15 A2997 RMK ICE MISG SLP211=
SPECI CYYN 150005Z AUTO 31011G16KT 9SM -SN CLR M13/M15 A2997 RMK ICE MISG SLP210=
METAR CYYN 150000Z AUTO 32012KT 9SM CLR M13/M15 A2997 RMK ICE MISG SLP206=

Clearly shown as an automated reading. Note the one-hour spacing unless it's a Special, where the weather changed too rapidly to wait for the next hourly. It started snowing at 0005Z so the machinery noted that. It stopped snowing at 0023Z so it noted that, too.
 
I think I am seeing the discrepancy. METARS that are found online are updated hourly. METARS that are found on the radio or telephone are updated every few minutes. Look at aviationweather.gov/metar. Compare that by calling the phone number or by monitoring the radio for a local airport.
 
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Gilbert Buettner said:
I think I am seeing the discrepancy. METARS that are found online are updated hourly. METARS that are found on the radio or telephone are updated every few minutes. Look at aviationweather.gov/metar. Compare that by calling the phone number or by monitoring the radio for a local airport.
Click to expand...
When you're calling or listening on the radio, you aren't getting a METAR, you're directly accessing the ASOS/AWOS/etc.
 
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Lindberg said:
When you're calling out listening on the radio, you aren't getting a METAR, you're directly accessing the ASOS/AWOS/etc.
Click to expand...
True.

When the weather is good, I usually fly four or five days a week. So, when I get up, I pour a cup of coffee, open my iPad and look at the weather for my airport and others nearby. Foreflight displays the weather, not current, but recent, as METARS. Updated far more often than hourly. The source of that METAR? ASOS or AWOS.
 
MajorTurbulence said:
While I have had an occurrence like yours with my PA28-181 O360A4M, it was after doing low power IFR practice approaches when my engine stumbled on the missed approach with insertion of full power. Fortunately, I was immediately on top of it with carb heat but did not leave it in long enough(should have left it on a minute or more).
Click to expand...
My Archer II will get carb ice in the air. Never on the ground. For my Archer when applying carb heat (when carb ice present), I find that it runs worse in the first 1 or 2 minutes when applied (which I consider validation that it was carb ice). At 3 or 4 minutes, power is back to normal. I keep the carb heat on for a full 10 mins to make sure no residual moisture is left that is going to refreeze when carb heat is turned off. I always hit the timer when carb heat is turned on. I also readjust the mixture when carb heat is turned on, adjust again after 3 or 4 minutes and adjust again when carb heat is turned off.

After a XC flight when conditions seem ripe for carb ice even if I have not noticed any problems, I will turn on the carb heat far enough out that I can get 10 mins of carb heat while still having time to turn off carb heat prior to landing checklist. In the Archer, carb heat is OFF for takeoff and landings.

My understanding is that carb ice forms significantly different between a Piper and a Cessna.
 
Discussions like this make me wonder why fuel injection is not more common.
 
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