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Thread: Compass Calibration Executive Panel

  1. #1
    Senior Member turbopilot's Avatar
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    Default Compass Calibration Executive Panel

    When my new Carbon Cub arrived magnetic heading on my Dynon FlightDEK-180 was way off. So I dove into the FlightDEK-D180 installation manual and found the remote compass calibration instructions. Then found a compass rose and went through the full compass calibration.

    Everything seemed to check out on the ground but once back up in the air north south readings were better but east west readings were up to 20 degrees off.

    I double checked the EDC-D10A compass module installation under the right wing. Everything looked right. Checked the area for magnetic fields with hand held compass. No problems.

    Then I started working my way through the electrical system switching on different boxes. Everything looked right except for the landing light switch. On an easterly heading in the hangar turning on the landing light swings the about 9 degrees. I normally fly with the landing light on for visibility so it would appear at least some of my compass error is coming from the landing light circuit.

    I need to make another flight now with the landing light off and check the error. Unfortunately, I don't recall whether I had the landing light on during my last calibration, so I may have to go back and do the compass calibration again.

    Anyone else have compass calibration issues with the Executive Panel?
    Bob Anderson, CC11-00316, N382RA

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    Senior Member Centmont's Avatar
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    Default Re: Compass Calibration Executive Panel

    Anyone else have compass calibration issues with the Executive Panel?
    Not with the executive pannel, but I have had with a smaller Dynon. Make shure you calibrate that compass with the tail picked up to full level flight attitude...second, mine hardly works well with the landing light on and I have been unable to fix that problem. We all still have two more compasses...one Garmin and the old whiskey. Ralph

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    Senior Member turbopilot's Avatar
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    Default Re: Compass Calibration Executive Panel

    Quote Originally Posted by Centmont View Post
    Make shure you calibrate that compass with the tail picked up to full level flight attitude.... Ralph
    That's interesting. I did double check that the remote compass module was mounted within 1 degree of the Dynon but the installation manual said nothing about leveling the tail. Can't hurt.
    Bob Anderson, CC11-00316, N382RA

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    Senior Member turbopilot's Avatar
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    Default Re: Compass Calibration Executive Panel

    Ok, I think I understand the compass calibration problem with the Dynon FlightDEK-D180 and the companion remote compass the EDC-D10A. There are several issues to consider in setting up the Dynon DEK-D180 in the Carbon Cub. Took four trips to the compass rose but I finally got it calibrated. Early hint that your compass is out of calibration is by looking at the wind vector. On easterly headings I would show winds of 25 to 30 mph when I knew the winds aloft were light and variable. Dynon just runs the math between magnetic heading and GPS track from the Garmin 375. Garbage in garbage out.

    First I recommend everyone with the Executive Panel find and become familiar with the FlightDEK-D180 Installation Guide. This is a very well written guide.

    First thing to check is the orientation settings of the EDC-D10A remote compass. The remote compass can be found in the bottom of the left wing.



    Check this box very carefully for orientation. The remote compass must be installed within one degree of orientation as compared to the Dynon DEK-180 on the instrument panel in pitch, roll and yaw. This is not an easy measurement to check since there are so many angles: DEK-180 is pitched down against flight level while the wing is angled then you have the pitch angle on the ground of the airplane which depends on what tires are mounted. Anyway after measuring a bunch of angles I determined that my remote compass box was 5 degrees pitch down as compared to the Dynon DEK-180. I adjusted it.

    Next out to the compass rose. I did this three times. The calibration seemed to go right by the book but each time I flew after the calibration I would have good readings North/South but easterly reading would be way off (15 degrees nominally) and westerly headings off by about 7 degrees.

    Then I saw the post about doing the calibration with the tail in the flight position. This is not covered in the installation guide. My hangar happens to face due east. I found out that by raising and lowering my tail to flight position an easterly heading would change around 7 degrees while the whiskey compass was unchanged.

    So back to the compass rose this time with Ben Hodges of California Cubs where we set about to calibrate my airplane and his Carbon Cub by raising the tail to the flying position for the calibration. This is a two man job and takes some time.



    After completing this calibration everything checked out perfect in the flight test. I arrived back at San Luis Obispo with a wind check at 100' for runway 29 at 290 and 16 knots. Wind vector on the Dynon was straight on the nose at 19 mph.

    So you have to calibrate the Dynon remote compass in the cruise flight position. Easiest way to to this is to set the horizon pitch in flight and use it as a reference on the ground. Remember depending on which sized main gear tires are installed will determine how high the tail needs to go to be in the flight position.
    Last edited by turbopilot; 04-28-2010 at 06:59 AM.
    Bob Anderson, CC11-00316, N382RA

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    Default Re: Compass Calibration Executive Panel

    Turbopilot ---
    How did you make your angle measurements?
    Sounds like I need to buy a serious digital inclinometer/protractor/level.
    Holding +/- one degree in three axis between the panel and wing units is almost impossible without some very good equipment.
    Ah well --- I have been thinking of buying a digital inclinometer for my home machine shop for machine setup. I remember one on sale for about $100.

    Did you find the angle adjustments on the wing remote difficult to make?
    It looks like the mounting adjustments could improved upon.
    Did you put thread-locker on the nuts to keep them from moving?

    It looks like the remote is close to the landing light in the same wing.
    I guess that's a separate issue that we can't solve.
    Bill
    Last edited by seastar; 04-30-2010 at 06:42 AM.

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    Senior Member turbopilot's Avatar
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    Default Re: Compass Calibration Executive Panel

    Quote Originally Posted by seastar View Post
    Turbopilot ---
    How did you make your angle measurements?
    Sounds like I need to buy a serious digital inclinometer/protractor/level.
    Holding +/- one degree in three axis between the panel and wing units is almost impossible without some very good equipment.
    Ah well --- I have been thinking of buying a digital inclinometer for my home machine shop for machine setup. I remember one on sale for about $100.

    Did you find the angle adjustments on the wing remote difficult to make?
    It looks like the mounting adjustments could improved upon.
    Did you put thread-locker on the nuts to keep them from moving?

    It looks like the remote is close to the landing light in the same wing.
    I guess that's a separate issue that we can't solve.
    Bill
    Yes, I used a digital inclinometer and a bunch of head scratching. Measure the floor, measure the Dynon, then measure the screw holes on the wing then lower the remote compass to the floor and try to true up the remote compass to the Dynon. It will take a while. Then do the compass calibration.

    The landing light issue needs some work. Maybe a shielded wire.
    Bob Anderson, CC11-00316, N382RA

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    Default Re: Compass Calibration Executive Panel

    A twisted pair cable for the landing light will solve the problem.
    They have been used for years to cancel adverse magnetic fields near a compass.

    A shielded pair does not shield the magnetic field, only the elecrostatic field.
    It will be difficult to fish a new cable to the light.

    The twist needs to be very small - ie, lots of turns/foot.
    I have made them with an electric drill.
    Bill

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