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Carbed Ice


Witch
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I got to wondering about this the other day whilst beating the air into submission; is carb ice really that big a deal? Does it form or build rapidly or slowly?

 

During the flight, the frakking carb heat assist kept turning the heat off and the temperature would get below 10*. I never noticed any change in the engine, but then I was thinking that maybe there wasn't enough water in the air or cold enough to form it.

 

Have any of ya'll experienced carb ice?

 

Later

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Just because ice didn't form doesn't mean that it can't. If there is moisture in the air (not just visable moisture, but humidity above 50%) and you let the carb air temp drop, there is a possibility it will form. If it does, you can find yourself in a world of hurt. I haven't had it happen personally, but then again I always incorperate my CAT guage into my scan. My question is... Why was your carb heat assist continuously turning off your carb heat? It shouldn't do that in straight and level flight and a quick scan when you're at cruise altitude should remedy it.

 

As far as whether or not it's a big deal, anything that is going to cause you to loose RPMs is a big deal. Especially if it happens at a time when you realize you need to pull pitch with a quickness. It can also cause your engine to crap the bed... Definately not a good thing unless you really enjoy autorotations.

 

J-

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As Vanilla Ice once said .... All right STOP, collaborate and listen.....

 

If you are in straight and level flight, pulling power above 18" MP then your carb icing will still occur but there's more chance of it on a low power setting, lower than 18" and the lower you go the more chance you have of a faster ice build up. Engine roughness in helis can sometimes be hard to detect fast enough which is why you don't want to mess with it.

 

I thought the heat assist was directly linked to your collective angle? I know there is a manual override on this, maybe yours is not working correctly? I'd get someone to check it out.

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I prefer this version

 

 

As for the original discussion on carb ice - as I understand it, whether or not it builds quickly, you won't find out about it until it's too late. As the ice builds up and chokes the air intake, the governor opens the throttle to compensate. So if you don't happen to notice the governor gradually increasing the throttle, you may not be aware that you have an ice issue until your RPM drops or your engine quits. Neither situation sounds appealing to me. I enjoy a good auto as much as the next guy, but I'd rather it wasn't a forced one! I'd just as soon pull carb heat and not have to worry about ice. The school I trained at had a few instances of fouled plugs that were thought to be a result of excessive carb heat usage. Regular cleaning of the plugs has kept those instances few and far between though. I know I'd rather have a fouled plug than a total engine failure.

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This is a GREAT VIDEO OF CARB ICE!!! IF you watch the WHOLE video you will see carb ice form and you will see what happens when CARB HEAT IS PULLED!!

 

This video shows ACTUAL CARB ICE!

ENJOY!

 

http://video.google.com/videosearch?q=carb...emb=0&aq=f#

 

I would look at that, but unfortunately your font wasn't quite big enough.

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I enjoy a good auto as much as the next guy, but I'd rather it wasn't a forced one! I'd just as soon pull carb heat and not have to worry about ice. The school I trained at had a few instances of fouled plugs that were thought to be a result of excessive carb heat usage. Regular cleaning of the plugs has kept those instances few and far between though.

 

Wussy... Forced autorotations are so much more fun! ;)

 

I had my first run-in with fouled plugs during a night flight back from San Diego (luckily with an instructor) about a month ago. After start-up as I was doing my hover checks, I got a sudden drop in power and uncommanded yaw. Not nearly as much as in an engine failure, but enough for me to put it back down immediately. I had never really recieved much instruction on that so after we called the chief instructor, the CFI started it back up with a slightly leaned mixture and that fixed it. Pretty scary initally though for a low-timer like myself.

 

J-

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Wussy... Forced autorotations are so much more fun! ;)

 

I had my first run-in with fouled plugs during a night flight back from San Diego (luckily with an instructor) about a month ago. After start-up as I was doing my hover checks, I got a sudden drop in power and uncommanded yaw. Not nearly as much as in an engine failure, but enough for me to put it back down immediately. I had never really recieved much instruction on that so after we called the chief instructor, the CFI started it back up with a slightly leaned mixture and that fixed it. Pretty scary initally though for a low-timer like myself.

 

J-

As with any other power-limited situation I was trained to try to find pavement and run it on

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Well, that was entertaining. As for that carb ice vid, it seems to take a while to form, and take a while to remove.

 

I've just never noticed any power loss, and got to wonderin' if carb ice would cause immediate power loss, or if it were gradual. The carb heat assist keeps turning the heat off, and I'd notice the carb temp kept going down, thus causing me to apply carb heat. I really want to put vise grips on that carb heat thing just to keep it applied.

 

Also, that font is too big for me to read.

 

Later

Edited by Witch
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I won't write this in large font...

 

There is a great video that is shown in the Robinson Safety Course. A new pilot that supposedly didn't pull his carb heat...and he died with his wife on his first flight after becoming a pilot. Granted this was in England...but it put enough fear in me to pay attention to the carb heat all of the time. There are a few documented events where this has happened and that is enough for me. When it makes the engine run rough and then quit - or just make it quit before you know it - then it's best to pay attention to that yellow arc.

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Witch- only once, flying at night. Maybe 50-55 outside air temp. I dont remember any visible moisture, I noticed the governor cranking up the throttle in my hand very slowly. No wind or turbulence, so the throttle should not be changing. I checked my airspeed....it was the same, again no reason for an increased demand. At that point I quickly reached over and pulled full carb heat. Within about 10 seconds everything was back to normal. I always figured this was a case of carb ice just beginning to form.

 

Lucky, I was 700 AGL over the 210 freeway with the Rose Bowl and golf course to my left, the 10 lane freeway under me (with very light traffic) and the Pasadena PD heli-port about 1/4 mile ahead. I guess if it had to happen, it probably would have turned out ok.

 

However my take is this. It costs you nothing. On take off you can pull the heat way down to add power....you are not going to ice up in 10 seconds of take off, especially with the butterfly wide open. But once you are up, pay attention and keep the needle well out of the yellow range....again, it costs you nothing to keep the carb nice and toasty, and the alternative isn't really a great one.

 

Fly safe,

 

Goldy

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Yeah Goldy, I kept having to pull carb heat to keep the carb toasty, but that dang carb heat assist is a pain. In 41J, when it was pulled, it stayed. 92U sucks.

 

Hey Deerock, I saw that vid. It bites big time that it iced over and got the rotor stall. Hence the reason to keep the heat on. Like I said, I want to clamp the device in the on position.

 

Later

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Yeah Goldy, I kept having to pull carb heat to keep the carb toasty, but that dang carb heat assist is a pain. In 41J, when it was pulled, it stayed. 92U sucks.

 

Hey Deerock, I saw that vid. It bites big time that it iced over and got the rotor stall. Hence the reason to keep the heat on. Like I said, I want to clamp the device in the on position.

 

Later

 

 

You might wanna have that checked out. I've never had a carb heat assist turn off my carb heat if I wasn't making drastic changes with the collective. I piss off the mechanics at my school on a regular basis making them fix things that everyone else lets slide ;)

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My dad had an engine stop due to carb ice in his Cessna 172. Somewhere down the line he got some off information that one should get rid of carb heat on landing so one can have full power available in case a go-around is needed. I don't know where he came up with that but he tried it one cool fall afternoon on short final. He said his engine quit with in about 5 secs of pushing the carb heat off. Lucky for him he was on short final to a runway so he just continued the landing with out power. It was a very good learning experience though.

 

Keep the needle out of the yellow!!!

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My dad had an engine stop due to carb ice in his Cessna 172. Somewhere down the line he got some off information that one should get rid of carb heat on landing so one can have full power available in case a go-around is needed. I don't know where he came up with that but he tried it one cool fall afternoon on short final. He said his engine quit with in about 5 secs of pushing the carb heat off. Lucky for him he was on short final to a runway so he just continued the landing with out power. It was a very good learning experience though.

 

Keep the needle out of the yellow!!!

 

 

Yikes! That's kinda like telling people that the stop signs with the white borders around them are optional. Yes, people have fallen for it.

 

J-

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