wireweinie
FOUNDER
Palmer, AK
Is that a thing? I always thought that was required, at least with a carb. And even with fuel injection it becomes your 'alternate air' source.
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Carb Ice- ENGINE SHUT DOWN
- Thread starter J5Ron
- Start date
Is that a thing? I always thought that was required, at least with a carb. And even with fuel injection it becomes your 'alternate air' source.
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CenterHillAg
PATRON
Texas Coast
Definitely not a thing. Just something an old operator set in his ways did.
RVBottomly
PATRON
Asotin County Washington (KLWS)
Then there is the doof like me who, last week as I entered the pattern, reached down to pull out carb heat. Engine stopped. I looked down and saw it was mixture I had pulled out. Shoved it back in and everything came back to normal.
Still not fully used to the airplane. The knobs are next to the throttle on both sides and they feel the same. One of those human factors things that people didn't worry about in 1946, I guess.
Still not fully used to the airplane. The knobs are next to the throttle on both sides and they feel the same. One of those human factors things that people didn't worry about in 1946, I guess.
skywagon8a
MEMBER
SE Mass MA6
You're not a doof. If you do it again, yes you are. Good lesson learned, safely.
sj
Staff member
Northwest Arkansas
I recently had a student do this to me in an airplane with the carbheat and mixture right next to each other and exactly the same type knob although obviously different colors. We put a McFarlane vernier mixture cable in and I hope that solves the problem��
spinner2
MEMBER
Montana
You're not alone.
when I built my Cub I used the same type knobs side by side too. One red and the other black. On a night landing on final I pulled the mixture instead of carb heat and it got quiet quickly. Fortunately it restarted quickly too.
like SJ mentions, I changed the mixture to a vernier type and hopefully smartened up a bit.
cubdriver2
FRIEND
upstate NY
I was hopping rides years ago in a homebuilt Great Lakes 2T1A powered with a 180 hp Ranger. I had a 70+ friend in the front seat. He wasn't wearing a flight helmet and his large ears were sometimes flapping in the wind. I discovered that if I used a little left rudder his right ear would flutter and visa versa for the left. I was amusing myself with his ear exercises while coming low over the west ridge of the airport and reached down and pulled the carb heat knob. Everything went silent for a few seconds till I realized my mistake.
Glenn
Glenn
RVBottomly
PATRON
Asotin County Washington (KLWS)
Now I think I'll be chuckling all morning. Distracted by ears! Thanks, Glenn.
Coeur d'Alene, ID
What type of fuel? I don’t think carb heat would work very well with the engine off, except as alternate air. I have a friend that had very similar happen in a borrowed airplane that the owner had been burning ethanol unleaded in (he tested the fuel after and lots of water settled out). The engine may have swallowed a big enough amount of water to quit. It also restarted and then he needed carb heat, we assumed because the water in the fuel iced in the Venturi easier than fuel without water/ethanol.
Sent from my iPad using SuperCub.Org mobile app
fancypants
FOUNDER
IL
I put a brand new Marvel carb on my C90 at last overhaul. Flew it for a couple hundred hours last year without any incidences of carb ice. Had to get it overhauled a few months ago due to some water accumulation and rust in the accelerator pump circuit. After overhaul I'm getting carb ice pretty regularly. Haven't quite figured that one out yet.
fancypants
FOUNDER
IL
I had mine done by Bob Bana at RLB Accessory Service in Addison, IL. Not your typical repair station, as it's run out of his basement. He cracked opened the carb in his kitchen to show me the problem. Old-timer that knows his stuff and doesn't mind sharing his knowledge. He was able to turn it around in a day, which probably isn't typical. He's also done some other work for me in the past - new hoses, mags, etc.
If he wasn't available I probably would have taken it to Aircraft Systems in Rockford.
If he wasn't available I probably would have taken it to Aircraft Systems in Rockford.
Fascinating. In 2021 I’d expect we’d know more about carb icing. My 0-520 doesn’t make ice. Others I know use carb heat continuously. I don’t get it. I do wonder if fuel flow is related. I’ve never been an aggressive leaner and the only time I’ve experienced ice was in a low power descent where I hadn’t adjusted mixture on the way down.
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fancypants
FOUNDER
IL
Yeah, it's odd. I don't have any indication of an induction leak before or after, so fuel flow/mixture at the carb seems like the only thing that could have changed. I've got a ton of data from the EI engine monitor that I can use to deduce a probable cause. Project for a snowy day.
cubdriver2
FRIEND
upstate NY
Coeur d'Alene, ID
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
My thoughts
Continental Engines (C-65, C-90, 0-200, 0-235, etc) all have the intake tubes outside the sump. They will all ice at the drop of a hat. Most POH's for these engines will say something like..."Apply Carb Heat before a reduction in throttle" or something like that.
Lycoming engines have the intake tubes going through the oil sump so the air is heated somewhat before it goes to the engine. As a result these engines are less likely to ice (not that they won't but somewhat less likely) and the older POH's all say something along the lines of...."Carb Heat, as required"
The newer aircraft with newer POH's will default to always applying card heat due to a few lawsuits.
For me..... when I fly a "C" engine..... I always apply carb heat....so I use a CGUMPSS check in which C=carb Heat.... then Gas, Undercarriage, Mixture, Prop, Seatbelts, Safety (= CLEAR, CLEAR, CLEAR)
When flying a Lyc engine I use it when I feel I need it. I have had LOTS of carb ice instances flying floats in SE Alaska in 50 degree temps and light rain. Landed, go idle, engine quits because I had some ice.
Another thought for detecting it. Look at where the throttle knob sits on your throttle box at say 2400 RPM. Maybe put a mark there. When flying in icing conditions do an occasional check of where the throttle is. If it is further forward of that mark to hold 2400 RPM you may be iced.
Also be careful leaning. If you have ice and lean it out a little the engine will pick up a few RPM as you just fixed the fuel/air mixture to accommodate the ice (again.....your throttle position will be further forward as well). But if you have leaned for ice then later introduce carb heat the mixture will initially go too rich then too lean as the ice melts out. The engine may stall, or perhaps even quit in this process. Been there done that.
StewartB made a good point above. Every engine is different. Some never ice and others get ice very quickly. I spent some time flying a couple of 206's this summer. Both nearly identical FWF. But one was extremely prone to Vapor lock, the other hardly ever. Sometimes this stuff is just black magic.
Just (perhaps) a little knowledge to put in your bag of tricks.
Hope this helps
Bill
Continental Engines (C-65, C-90, 0-200, 0-235, etc) all have the intake tubes outside the sump. They will all ice at the drop of a hat. Most POH's for these engines will say something like..."Apply Carb Heat before a reduction in throttle" or something like that.
Lycoming engines have the intake tubes going through the oil sump so the air is heated somewhat before it goes to the engine. As a result these engines are less likely to ice (not that they won't but somewhat less likely) and the older POH's all say something along the lines of...."Carb Heat, as required"
The newer aircraft with newer POH's will default to always applying card heat due to a few lawsuits.
For me..... when I fly a "C" engine..... I always apply carb heat....so I use a CGUMPSS check in which C=carb Heat.... then Gas, Undercarriage, Mixture, Prop, Seatbelts, Safety (= CLEAR, CLEAR, CLEAR)
When flying a Lyc engine I use it when I feel I need it. I have had LOTS of carb ice instances flying floats in SE Alaska in 50 degree temps and light rain. Landed, go idle, engine quits because I had some ice.
Another thought for detecting it. Look at where the throttle knob sits on your throttle box at say 2400 RPM. Maybe put a mark there. When flying in icing conditions do an occasional check of where the throttle is. If it is further forward of that mark to hold 2400 RPM you may be iced.
Also be careful leaning. If you have ice and lean it out a little the engine will pick up a few RPM as you just fixed the fuel/air mixture to accommodate the ice (again.....your throttle position will be further forward as well). But if you have leaned for ice then later introduce carb heat the mixture will initially go too rich then too lean as the ice melts out. The engine may stall, or perhaps even quit in this process. Been there done that.
StewartB made a good point above. Every engine is different. Some never ice and others get ice very quickly. I spent some time flying a couple of 206's this summer. Both nearly identical FWF. But one was extremely prone to Vapor lock, the other hardly ever. Sometimes this stuff is just black magic.
Just (perhaps) a little knowledge to put in your bag of tricks.
Hope this helps
Bill
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Crash Jr.
Registered User
Anchorage, AK
Just a small point of correction. Lycomings still have the carburator before the sump so the air passing through the carburator isn't heated beforehand. I think the tendency for Lycomings not to make as much carb ice is due to the carb being attached directly to the warm sump so the carburator gets heated by the heat radiating from the oil sump.
Crash Jr.
Registered User
Anchorage, AK
Fair point. Just seems like the consensus is that 4 cylinder Continentals make more carb ice than 4 cylinder Lycomings. Perhaps this is not the case?
My experience has been with an A65 that makes ice at the drop of a hat, a C85 that has never had carb ice but has carb heat used religiously and an O-360 that has never had an issue with carb ice. No carb temp gauges installed so no idea if the temp is different. Just an opinion based on extrapolation. The Continental carb ice thing could also be related to the fact that most small continentals use Stromberg carbs that may be more prone to icing.
My experience has been with an A65 that makes ice at the drop of a hat, a C85 that has never had carb ice but has carb heat used religiously and an O-360 that has never had an issue with carb ice. No carb temp gauges installed so no idea if the temp is different. Just an opinion based on extrapolation. The Continental carb ice thing could also be related to the fact that most small continentals use Stromberg carbs that may be more prone to icing.
We’re all taught that air temp drops as air pressure drops after passing through the venturi. Simple science. We’re all taught carb icing probability is relative to a relationship of OAT and humidity. That said, why don’t fuel injection servos ice up? Probably no venturi required since it doesn’t need to pick up fuel there. I should have stayed in school.
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skywagon8a
MEMBER
SE Mass MA6
Because the fuel is injected at the intake valve inside the warm cylinder head. The cooling effect of the vaporizing fuel is not in the butterfly/venturi area. There is always the possibility of ram ice accumulating, though this is minimal.
BC12D-4-85
SPONSOR
Fairbanks, AK.
I apologize for the repetition but adding a simple manifold pressure gauge can help detect icing. Requires level flight and steady throttle/rpm to maintain indicated pressure, but will drop before most mechanical tachs will as the throttle plate becomes restricted in my experience. If icing detected apply heat and lean to maintain MP. If chasing rpm with throttle as ice builds pay attention to the normal throttle position required to achieve rpm as noted above in #51.
Gary
Gary
Thought I would follow up…was a beautiful day here in Valdez…so decided to fire up…flew nearly two hours, trouble free, carb ice free, engine stumble free…plane ran great and seemed to produce plenty of power…was heading in and I wanted to take a look up Valdez Glacier, so I diverted and headed up the glacier.. ( Mistake #1…that wasn’t in my flight plan that I left with my wife!). I was a couple miles up and could feel a slight rumble in my floor board…pulled carb heat, and for a second seemed better…I decided I better just head on home…then I happened, engine rough, stumbling, coughing…it was bad…pulled carb heat, nothing, messed with mixture, nothing, check mag switches, seemed fine…began it look for what might be the best place to set down on the glacier. Pulled mixture just a bit and carb heat just a bit, reduce power slightly and kept it running…made it home. Anyways, I decided to do a compression check after I settled down…
#4 was down to 30…
#1 was down to 60…
3&4 were 72 and 68 respectively…
Anyways…I’m down on the ground for awhile until I figure this out!
if there is one thing I know for certain…don’t deviate from your flight plan….
Thanks for the input folks!
#4 was down to 30…
#1 was down to 60…
3&4 were 72 and 68 respectively…
Anyways…I’m down on the ground for awhile until I figure this out!
if there is one thing I know for certain…don’t deviate from your flight plan….
Thanks for the input folks!
