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Thread: Replacement Airspeed Indicator

  1. #1

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    Replacement Airspeed Indicator

    I have a UMA airpseed indicator. It's only a couple of years old- but is completely inaccurate. It's reads about 20 MPH too slow. My AV-30- that runs on the same pitot is spot on.

    I want a different airspeed indicator. I guess it needs to be certified as a primary as the AV-30C is not.

    Any suggested models?

  2. #2

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    What kind of pitot tube do you have? Some can be adjusted. If you get a new one get one that will go to 20 MPH. DENNY

  3. #3

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    I wonder if early PA-18s used the J3 pitot system? In my limited experience no "certified" airspeed indicator will be accurate in a J3.

  4. #4

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    The av30 is accurate. Its plumbed together on the same pitot. I think its the gauge

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    Kind of like a compass pointing in one direction. Have a sticker made of an ASI that reads the speed you want it to and stick it over the bezel

  6. #6
    BC12D-4-85's Avatar
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    Quote Originally Posted by Cardiff Kook View Post
    The av30 is accurate. Its plumbed together on the same pitot. I think its the gauge
    Hook up a tube to the gauge and go driving with the tube end out the vehicle window facing the breeze

    Gary

  7. #7

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    Just a general pontification on airspeed indicators. The important thing is to know what the airspeed number really means. If you indicator is off by 5 mph but you know what the indicated speed is (be it faster or slower) when it stalls than it for that purpose it is doing its job. Same for flight planning, wind speed calculation, flap speed, ect. Off by 20 mph on the bottom and top send gauge in for repair or get a new one. If it a newer gauge send it in and see what a calibration will cost.
    DENNY

  8. #8
    supercrow's Avatar
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    Just as an interesting note. When I put my AV-30 in a year ago, I plumbed the single pitot to both it and the airspeed indicator. They were 10 or more different in reading and my airspeed had always been very close to my GPS. With them hooked together my original gauge was the one that was off. I installed another pitot/static unit just outboard of the jury struts and dedicated it to the AV-30. Numbers of all three units are together now. Air Spruce has a neat pitot static tube that I installed into an inspection cover and put it into the bottom of the leading edge just forward of the spar. I am inclined to think that the static was the issue. Didn't try to dig too deep about why it wouldn't work hooked to both so your issue may differ but this took care of mine very nicely.
    Thanks Cardiff Kook thanked for this post
    Likes stewartb liked this post

  9. #9

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    Quote Originally Posted by supercrow View Post
    Just as an interesting note. When I put my AV-30 in a year ago, I plumbed the single pitot to both it and the airspeed indicator. They were 10 or more different in reading and my airspeed had always been very close to my GPS. With them hooked together my original gauge was the one that was off. I installed another pitot/static unit just outboard of the jury struts and dedicated it to the AV-30. Numbers of all three units are together now. Air Spruce has a neat pitot static tube that I installed into an inspection cover and put it into the bottom of the leading edge just forward of the spar. I am inclined to think that the static was the issue. Didn't try to dig too deep about why it wouldn't work hooked to both so your issue may differ but this took care of mine very nicely.
    Interesting. Have a link to that air spruce unit or p/n?

  10. #10
    supercrow's Avatar
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    Part no. 15144 I think. Take a look at the picture on the site. Also I posted incorrectly about where I located it though I think that would work. Was thinking of my AV-30 probe. I put the pitot static tube in a high speed cover just outboard or the rear jury strut on the left wing and put a few #4 pk's in it to hold the position. I also installed a pitot cover. The number for that is listed along with the above number in the spruce website.

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