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Bad decision/good decision? What doesn't kill us...

cubflier said:
Behindpropellers said:
Like landing on the moon :)

Do you ever worry about the ice breaking off into the crevasse?

As I said, were on two different spectrums of flying.

Tim,

On glaciers I worry about many things. But as far as the video, that ice is very solid and to an extent you can read whether the ice is solid or not from the air.

My point was not to make the distinction between spectrums of flying but more to make a point that the application of carb heat and switching tanks should be instinctive whether you are on a final to land on a glacier or on final to Anchorage International. Also, not all approaches can be accomplished safely without the application of power.

I'm not sure everyone out there understands how quick a cub engine will light back up if you accidentally run a tank dry. All you have to do is switch tanks. I had one quit ( from bad owner/builder (not me)fuel line installation) right after take off in the Brooks. An instinctive switch to the other tank gave me power just before I balled it up in the stream bed below.

Good execution of emergency procedures can be a life saver.

Jerry

Good points.

Just don't switch to the empty tank :eek:
 
cubflier said:
I'm not sure everyone out there understands how quick a cub engine will light back up if you accidentally run a tank dry. All you have to do is switch tanks.

Jerry

Jerry,

You are correct, of course, but it sure SEEMS like a WEEK before that engine restarts......not that I've ever actually experienced that of course... :roll:

And, I knew at least one person who didn't get there quickly enough right after takeoff and died in the ensuing arrival...

Your point is well taken--these procedures should be almost reflexive

MTV
 
mvivion said:
cubflier said:
I'm not sure everyone out there understands how quick a cub engine will light back up if you accidentally run a tank dry. All you have to do is switch tanks.

Jerry

Jerry,

You are correct, of course, but it sure SEEMS like a WEEK before that engine restarts......not that I've ever actually experienced that of course... :roll:

And, I knew at least one person who didn't get there quickly enough right after takeoff and died in the ensuing arrival...

Your point is well taken--these procedures should be almost reflexive

MTV

And I know of one that came alive during touchdown on a sandbar (throttle still full) and it flipped over.

A "both" mod to the fuel selector and keeping it selected there when under 1000' agl solves this risk.
.
 
When referencing the carburetor ice probability charts, air temps below 10F seem to have a low to zero probability of carb ice development. I have had one time when flying in the 0-10F range with little to no moisture present in the atmosphere and when applying carb heat on midfield downwind approach to LZ at 4,500 MSL the engine actual had the normal RPM drop of 100-150 RPM but as I left carb heat on for my base to final leg it started to run even more rough and started to sound like it was going to quit. Almost as if the carb heat was causing ice to develop. Not sure why applying full throttle and putting carb heat into off position helped but it did and I decided to return to the airfield instead of carrying on in glaciated environs since it didn't quite make sense to me at the time.
I now have a hyper-awareness to carb ice due to another learning experience besides my cold weather ops lesson above but still am somewhat confused by cold weather carb heat ops. I still am not certain the best practice for carb heat application when temps go below 10F. Is it still the best practice to apply full carb heat each and every time power is reduced below cruise regardless of temp? OR are there actual atmospheric conditions that do not warrant the application at all? I sort of always thought that at temps well below freezing that moisture in the air was unlikely and that applying carb heat could actually introduce moisture.
So, what is everybody out there doing during their cold weather operations? Any hard and fast rules or lessons to live by?
 
When referencing the carburetor ice probability charts, air temps below 10F seem to have a low to zero probability of carb ice development. I have had one time when flying in the 0-10F range with little to no moisture present in the atmosphere and when applying carb heat on midfield downwind approach to LZ at 4,500 MSL the engine actual had the normal RPM drop of 100-150 RPM but as I left carb heat on for my base to final leg it started to run even more rough and started to sound like it was going to quit. Almost as if the carb heat was causing ice to develop. Not sure why applying full throttle and putting carb heat into off position helped but it did and I decided to return to the airfield instead of carrying on in glaciated environs since it didn't quite make sense to me at the time.
I now have a hyper-awareness to carb ice due to another learning experience besides my cold weather ops lesson above but still am somewhat confused by cold weather carb heat ops. I still am not certain the best practice for carb heat application when temps go below 10F. Is it still the best practice to apply full carb heat each and every time power is reduced below cruise regardless of temp? OR are there actual atmospheric conditions that do not warrant the application at all? I sort of always thought that at temps well below freezing that moisture in the air was unlikely and that applying carb heat could actually introduce moisture.
So, what is everybody out there doing during their cold weather operations? Any hard and fast rules or lessons to live by?

I was flying a C150 years ago in 5 degree f weather doing stalls. I applied carb heat and reduced power and the engine sounded like a snowcone machine and quit at 5000’. I got a restart at 500’
I repeated and got same result.
Returned to airport and explained what happened to my instructor, he said”no way, too cold” so back up we went and when i pulled carb heat ice began grinding through engine sgain so we called it a day.


Sent from my iPhone using SuperCub.Org mobile app
 
Flynlow, I think I either read your story or another very similar one somewhere else on here. Sounds like the carb heat in your instance was in fact introducing moisture, therefore allowing for ice development. Any conclusions you and your instructor came to? Hard to say since nearly all atmospheric conditions are unique but I'm talking those clear cold days with temps below 10/20F and minimimum visible moisture in your flying environment.
 
I know I have read the recommendation is not to run prolonged carb heat unless you can monitor carb temp, just don't remember where.
DENNY
 
MTV
How about in temps below 10-20F. No visible moisture in flying environment. Is it still applicable to apply carb heat every time reduced power operations prevail or will this potentially introduce moisture in this instance? I do winter fly and generally it is at 32 or below in my neighborhood. I know that if there is any moisture in the air at freezing or below temps that it wil be frozen and most likely visible. If no visible moisture however, does one operate the carb heat just the same as he does in summer conditions?
 
I've had ice form in below freezing air temps with prolonged carb heat. Saw it via a steady drop in manifold pressure. I like to install a 2 1/4" manifold pressure gauge on fixed prop engines for that reason. Just a brief check before power reduction is all I care to use in that situation.

Edit: A throttle venturi temp probe and gauge will note potential conditions for carb ice...but a manifold pressure gauge will quickly indicate if it's happening. The conditions necessary for a reliable indication are a constant throttle setting and level altitude. The ice formed restricts the incoming airflow which mimics closing the throttle. That makes for lower intake manifold pressure downstream of the carb.

Gary
 
Last edited:
The day I had the issue with ice was in Kansas but there was snow drifts on the ground that was a factor in the field i had picked to put down on so the air was likely relatively humid.
And yes I believe i related this story some time ago on this or another forum..
I know on a warm humid day the venturi will drop air temp as much as 70 degrees bringing the temp right down into the temps condusive for carb ice. I am guessing on a bitter cold day the temp rise called by carb heat and reduced power actually caused this temp to rise into this temp range. I know as soon as power was reduced and carb heat applied the snow cone machine effect was immediate.
My instructor was a very experienced crop duster with tons of hours and he was surprised and his reaction was also immediate "Lets go Home"
 
MTV
How about in temps below 10-20F. No visible moisture in flying environment. Is it still applicable to apply carb heat every time reduced power operations prevail or will this potentially introduce moisture in this instance? I do winter fly and generally it is at 32 or below in my neighborhood. I know that if there is any moisture in the air at freezing or below temps that it wil be frozen and most likely visible. If no visible moisture however, does one operate the carb heat just the same as he does in summer conditions?

Actually, the worst case of airframe icing I've encountered was at temps close to -30. There was haze in the air, which I assumed was "Arctic Haze" (whatever that is) and ignored. White airplane, ALL white, including skis. I was doing radio telemetry south of Bettles. Landed in Bettles and the plane fell out of the air at 70. Had rime ice on everything. I assume that haze was in fact fine supercooled water droplets. Windshield had defrost on, so stayed clear. Took three hours to build up.

That was the day I stopped saying "never".

So, I wouldn't necessarily assume there's no free water even at very cold temps.

As Gary says, best bet is have carb air inlet monitor, if temps are very cold, carb heat may raise the temps to the icing range. That said, 99.9999 % of the time in very cold temps, there is no free water.

MTV
 
Is it still the best practice to apply full carb heat each and every time power is reduced below cruise regardless of temp? OR are there actual atmospheric conditions that do not warrant the application at all? I sort of always thought that at temps well below freezing that moisture in the air was unlikely and that applying carb heat could actually introduce moisture.
So, what is everybody out there doing during their cold weather operations? Any hard and fast rules or lessons to live by?

As far as I know carb heat introduces heat into your carb inlet and that's all. The flying I do is mostly in the winter for backcountry skiing and the landings are around 7000ft with temps between 10f above to -20f. Colder than that, I cry and go home. I don't tend to use carb heat that much but still will use it to confirm that my mixture settings are correct since cruising around altitudes will be between 8 and 9k and I need to lean a fair bit. Carb heat is another way to confirm that I'm not running the engine lean. I still will apply some carb heat in pattern just to see what the carb is thinking and to prevent any surprises but beyond that, in general, I use carb heat much less under the conditions I described above.

All planes differ so keep that in mind. Just keep experimenting and you'll figure it out. But if you have a carb that keeps coughing, spitting and doing things at altitude defy what seems right the time may be right to let a component shop make it young again.

Good luck on your ski adventures,

Jerry
 
One old timer that flew early Taylorcrafts told me they used to lean the engine (probably Continental A or C-65's) and try to get them to backfire through the carb to melt ice. A lean fuel mixture is slow burning and if still flaming away when the intake valves open for a new combustion cycle that can ignite incoming fuel and air. Some early planes offered carb air heaters as an option until someone figured out what was causing stoppage. Even with them installed if the exhaust cools during descent there may not be enough heated air temp rise to melt the ice.

Gary
 
As far as I know carb heat introduces heat into your carb inlet and that's all. The flying I do is mostly in the winter for backcountry skiing and the landings are around 7000ft with temps between 10f above to -20f. Colder than that, I cry and go home. I don't tend to use carb heat that much but still will use it to confirm that my mixture settings are correct since cruising around altitudes will be between 8 and 9k and I need to lean a fair bit. Carb heat is another way to confirm that I'm not running the engine lean. I still will apply some carb heat in pattern just to see what the carb is thinking and to prevent any surprises but beyond that, in general, I use carb heat much less under the conditions I described above.

All planes differ so keep that in mind. Just keep experimenting and you'll figure it out. But if you have a carb that keeps coughing, spitting and doing things at altitude defy what seems right the time may be right to let a component shop make it young again.

Good luck on your ski adventures,

Jerry

Hi Jerry, this will no doubt display ignorance on my part, but I admit I have no idea how the use of carb heat would confirm your mixture setting is not too lean as you mention. Do you mind enlightening me (and anyone else who might have the question).


Sent from my iPhone using SuperCub.Org mobile app
 
Hi Jerry, this will no doubt display ignorance on my part, but I admit I have no idea how the use of carb heat would confirm your mixture setting is not too lean as you mention. Do you mind enlightening me (and anyone else who might have the question).


Sent from my iPhone using SuperCub.Org mobile app

Leaning with carb heat on is just a faster way to set the mixture than searching for the rich side of peak using the tach. For me, in the cub, I pull carb heat, usually on approach, and set the mixture to the point where the engine is not at a stumble.The result is a mixture setting yields a max performance rpm that is rich of peak setting. In the cub I typically use the technique for ski ops above 7k.

I lean with carb heat on in my Maule just to keep it from the occasional backfire on landing that breaks muffler baffles.

I have minimal engine monitoring (single point cht/egt) in both planes and over time this technique has proved easy enough to become habit. Another leaning technique that's handy on the ground is to lean on one mag. I know results will vary with different engines, since my old 150hp engine was a very different animal and leaning was not as big of a consideration nor was running it lean of peak.

Feel free to experiment.



Take care - Jerry
 
If it was traditional carb ice and the engine didn't respond to carb heat...how about actively working the throttle open and close to enable the accelerator pump to spray fuel? The pump outlet is typically in the venturi and down airstream of the throttle plate. Not sure if it would dislodge nearby ice but worth a try. Wonder if the pilot noted declining manifold pressure values prior to stoppage if the C-175 w/O-360 was equipped?

The NTSB report below notes some water presence in the carb float bowl. One winter I had an O-360 quit immediately/no slow loss of power presumably due to ice crystals forming in the float bowl that eventually blocked the inlet to the mixture metering valve, main jet, and discharge nozzle. The manifold pressure gauge never dropped prior to stoppage but the EGT showed a gradual uncommanded rise at full rich during the previous 30 minute flight. Applying carb heat had no effect. Pumping the throttle caused a rise burp in rpm, same for working the primer. As a last resort I ended up working the mixture control which apparently broke up the collected ice crystals and returned power. Air temps were well below freezing.

That may have been a contributing factor in this event:

https://www.ntsb.gov/about/employme...ev_id=20130202X10430&ntsbno=WPR13LA108&akey=1

Gary
 
Carb Ice so much to say.

Continental engines are more apt to generate carb ice than a Lycoming because the carb is mounted remotely from the engine. The Lycoming carb is attached to the oil sump which is warm enough to heat the carb reducing the propensity for ice formation. Have you ever looked at a Volkswagon carb and seen it all covered with frost? The Ranger engine had what is called a "hot spot" heater. There was a pipe from the exhaust which was plumbed into a chamber around the carb spider providing heat.

The evaporation of the fuel when it sprays out of the discharge nozzle causes a temperature reduction. As a result if the moisture laden inlet air temperature is above freezing it can turn to ice when it comes into contact with the vaporized fuel. It then builds up on the throttle plate and the venturi throat restricting it's opening. This is where the reduction in manifold pressure is noted. This also has the effect of slowly reducing the power because the venturi size is reduced.

Under that scenario the application of carb heat melts the ice.

If the carb heat seems to be inadequate you can increase the amount of heat by slowing the plane and going to full throttle/power. The greatest amount of heat is generated at low forward airspeed with the engine producing it's highest amount of heat. Low speed reduces the cooling of the engine thus the temperature in the heat muff will be the highest.

Now, on a clear cold winter day it is possible for the moisture in the air to be frozen dry ice crystals in suspension. These crystals can be so minute that the pilot may not even be aware that they exist. Under these circumstances the ice crystals can pass through the carb to be consumed in combustion causing no harm. Under these conditions if you apply carb heat out of habit and training the ice crystals will melt prior to entering the carb and then refreeze when they come into contact with the evaporated cold fuel then refreeze on the throttle plate and venturi. Now what? You already have the heat on. The only thing that I can suggest is to slow the plane at full throttle hoping that the temperature increase will be enough. If this works, shut off the carb heat and leave it off.
 
One of the nice things with the cgr-30p in the cub is the fuel flow. I get used to what the flow is at my normal cruise RPM. I looked down and saw the fuel flow was up a couple gph more than normal, pull the carb heat and it ran rough. Seems like with the sutton exhaust its more prone to carb ice. Didn't have much of an rpm loss if any, but the fuel flow was higher.
 
Carb Ice so much to say.

Continental engines are more apt to generate carb ice than a Lycoming because the carb is mounted remotely from the engine. The Lycoming carb is attached to the oil sump which is warm enough to heat the carb reducing the propensity for ice formation. Have you ever looked at a Volkswagon carb and seen it all covered with frost? The Ranger engine had what is called a "hot spot" heater. There was a pipe from the exhaust which was plumbed into a chamber around the carb spider providing heat.

The evaporation of the fuel when it sprays out of the discharge nozzle causes a temperature reduction. As a result if the moisture laden inlet air temperature is above freezing it can turn to ice when it comes into contact with the vaporized fuel. It then builds up on the throttle plate and the venturi throat restricting it's opening. This is where the reduction in manifold pressure is noted. This also has the effect of slowly reducing the power because the venturi size is reduced.

Under that scenario the application of carb heat melts the ice.

If the carb heat seems to be inadequate you can increase the amount of heat by slowing the plane and going to full throttle/power. The greatest amount of heat is generated at low forward airspeed with the engine producing it's highest amount of heat. Low speed reduces the cooling of the engine thus the temperature in the heat muff will be the highest.

Now, on a clear cold winter day it is possible for the moisture in the air to be frozen dry ice crystals in suspension. These crystals can be so minute that the pilot may not even be aware that they exist. Under these circumstances the ice crystals can pass through the carb to be consumed in combustion causing no harm. Under these conditions if you apply carb heat out of habit and training the ice crystals will melt prior to entering the carb and then refreeze when they come into contact with the evaporated cold fuel then refreeze on the throttle plate and venturi. Now what? You already have the heat on. The only thing that I can suggest is to slow the plane at full throttle hoping that the temperature increase will be enough. If this works, shut off the carb heat and leave it off.

Sometimes you can generate a back fire by going to one mag and goosing the throttle. The flame front from the back fire can usually shake loose ice on the throttle plate.
 
….Continental engines are more apt to generate carb ice than a Lycoming because the carb is mounted remotely from the engine. The Lycoming carb is attached to the oil sump which is warm enough to heat the carb reducing the propensity for ice formation......

Generally true, but.....
the Continental C-145 / O-300 engine has a sump-mounted carb, just like a Lyc 320.
but is notorious for carb ice in spite of that.
I had a couple episodes with it myself over the years.
 
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