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Thread: New bushing: Carburetor air box spring

  1. #1
    Member gderamel's Avatar
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    Default New bushing: Carburetor air box spring

    Found this spring working it's way through a friend's brand new (50 Hours TT?) Carbon Cub Carb Heat Air Box.

    Bad.jpg

    Had a stainless bushing machined up to fit in the aluminum flange off the Carb Heat Box.

    IMG_0028.jpgIMG_0029.jpg

  2. #2
    Senior Member Clay Hammond's Avatar
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    Default Re: New bushing: Carburetor air box spring

    Was this on George's plane?
    _______________________
    Clay Hammond

  3. #3
    Member gderamel's Avatar
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    Default Re: New bushing: Carburetor air box spring

    Yes.

    Not sure how many hours where on the plane... Fairly new, I think.


    Sent from my iPhone using Tapatalk

  4. #4
    Senior Member Dan L's Avatar
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    Default Re: New bushing: Carburetor air box spring

    I took the EX up for a flight this morning. We got an inch plus of rain and there had been fog and low stratus in the valley a few hours earlier so I made a check for carb ice. When I do that I like to look at the carb temp probe reading and noticed that it didn't get cooler when I pushed the cable knob back in. So I headed back to the hangar and pulled the cowl. The welded aluminum bracket had broken leaving the end of the cable sheath unsupported. And so the carb heat stayed on.

    image.jpg

    The break is right above my thumb. You can also see the two twists of safety wire around the sheath on either side of the clamp. I'd had a little slippage of the sheath in the clamp and this stopped it.

    I pulled the air box and made a new tab from thicker material. One rivet held it in place prior to welding so the clamp position will be the same.

    Looking at at the crack line I could see that there had been a crack present for some time before the final break today. Half of the crack line was dirty and half was clean.

    Something to to look at when the cowl is pulled. I have about 550 hours on the EX at this point.

    I've checked for spring wear as shown at the beginning of this thread and don't see any elongation of the hole.

    IMG_1272.jpg

    This image shows the new tab after welding. I made the replacement from .050" aluminum and riveted it to the stub that was left after the original broke. Then I located the new hole by placing the broken off piece where it had been and punched the new hole. The new tab was then welded along the original weld.

    It should hold up well considering the increased material thickness.
    Last edited by Dan L; 04-26-2016 at 10:17 AM. Reason: added second image
    Flying Carbon Cub EX #11 since 2011

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