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Thread: 912S - Carb Heat or Not??

  1. #1
    N82HB's Avatar
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    Default 912S - Carb Heat or Not??

    My airplane does not have carb heat. It has been that way for 350 hours, but that doesn't make it right. Should it have it? I would love some opinions...
    Kelly

  2. #2
    Senior Member Dorsal's Avatar
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    Default Re: 912S - Carb Heat or Not??

    I asked the same question while I was building and my research suggested carb heat was not necessary if your intake is drawing from inside the cowl. This is, of course, only what I found and chose to do and at 70 hours I have significantly less time on my plane than you do. I sometimes contemplate moving my air intake to the scoop (possibly a skosh more HP) in which case I would implement CH.
    Dorsal ~~^~~
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    Super Moderator Av8r3400's Avatar
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    Default Re: 912S - Carb Heat or Not??

    I took off the ducted carb heat system from my yellow plane. In doing so, I gained 200 static rpm from the loss of restrictions.

    The anecdotal information that I have heard, and believe, is that the only planes which have ice issues are the ones with the ducted carb heat setup on them. This is due to the intake just behind the prop taking in the colder air. With the intakes by the firewall the air is preheated by the ambient temp inside the cowling lessening the likelihood of ice.

    I have no scientific evidence to support this, but it does make logical sense.

    The liquid heating type of carb ice prevention does seem to be interesting, though.
    Av8r3400
    Kitfox Model IV
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  4. #4
    Senior Member Dorsal's Avatar
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    Default Re: 912S - Carb Heat or Not??

    Quote Originally Posted by Av8r3400 View Post
    I took off the ducted carb heat system
    Good to know, I can leave mine the way it is without the feeling there might be an extra fraction of a HP left on the table.
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

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    Smile Re: 912S - Carb Heat or Not??

    G`day Kelly
    For Canadian homebuilts it is mandatory according to Transport Canada to have some approved form of carb heat regardless of where the carbs are located. In order to meet this requirement (and also for my own piece of mind) I installed the small hot water manifolds that mount between the intake and the carbs. I have no operating experience prior to installation so are not able to comment on power loss,etc. They are always "on" therefore I just do not worry about icing.These units are available from Bob at Light Engine Service (780-418-4164) or possibly directly from Sky-Drive in UK.Supposedly the carb throat body maintains enough heat to prevent ice build up without preheating the intake air resulting in a noticeable power loss.

    Have fun

    Don

    KF5 Vixen C-FOXK
    912UL

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    Administrator DesertFox4's Avatar
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    Default Re: 912S - Carb Heat or Not??

    Kitfox2009- Good point. Required North of the border. I'd also go with the hot water manifold type if I felt the need. No issues with carb. ice yet with the intakes by the firewall. I do spend most my time in the desert so moisture usually isn't a problem. Unusual for dew points and temps to get within 10 degrees of each other.
    I'll deffer to the guys that fly in moister climates for their experiences in this matter.


    DesertFox4
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  7. #7
    N82HB's Avatar
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    Default Re: 912S - Carb Heat or Not??

    I just helped a friend bring a 912 powered Kitfox back from Iowa. It has the carb heat on it, but my first thoughts were the remove it. Weight, simplicity, and all those words kept creeping up on me.

    I know mine works fine, but I wanted some more input.
    Thanks so much,
    Kelly

  8. #8
    Senior Member jtpitkin06's Avatar
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    Default Re: 912S - Carb Heat or Not??

    I would like to offer up the following sobering facts on carburetor ice. The NTSB files are full of accidents caused by carburetor icing. Many of the reports have statements from the pilot such as:

    I thought (brand name) engines don’t get carb ice.
    I didn’t use carb heat because it’s a warm day.
    It can’t be carb ice because it isn’t (raining, snowing, sleeting, freezing)
    And my favorite...

    I flew for hundreds of hours without it and never had a problem.





    It's a safety feature. Use it.


    OK... I'm climbing down off my soap box, now.


    John Pitkin
    Greenville, Texas

  9. #9

    Default Re: 912S - Carb Heat or Not??

    You'd think fuel injection would have been advanced by Rotax years ago... as a standard feature. Why don't they?
    NOKITFOXYET

  10. #10
    Super Moderator Av8r3400's Avatar
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    Default Re: 912S - Carb Heat or Not??

    One word answer: Liability.

    Every time BRP approaches a manufacturer about fuel injection they all run away from "aircraft" usage due to liability. (This is per one of the people who is in the know at a Rotax service center.)
    Av8r3400
    Kitfox Model IV
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