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Thread: G3x horizon malfunctioned

  1. #1
    Senior Member TroyBranch's Avatar
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    Default G3x horizon malfunctioned



    On the last two flights I have had my Efis do this. I plan to recalibrate it so see if it solves it. It corrects itself in flight after a few minutes. Anyone else have this issue? Very concerning that it would even do this.


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  2. #2
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    Default Re: G3x horizon malfunctioned

    Has this just shown up out of nowhere recently, and how many hours have you flown it? Are you getting any error messages - red X or messages down in the right hand corner where the message pop ups are shown? What does the unit show when the aircraft is sitting static on the ground, does it show wings level - within a degree or so, depending on how level the surface it is sitting on - and depending on the main tire diameter, anywhere from 8 to 12 or so degrees nose up pitch?

    You could level the aircraft and compare to what you see, and then you could also go into the configuration mode and re calibrate the level of the GSU25 adahrs unit to the aircraft in the config mode. The G3X manuals are online via garmin, no special dealer access or anything to read or download them. Section 18 talks about how its mounted, Section 34 - specifically 34.4.5 talks about how the calibration is done.

    Garmin just released sw version 5.40 for the GDU46X display, you may want to upload that prior to doing anything else. It may or may not make any difference but its the simplest and easiest thing one could start with.

    Good luck

    Mike Sutton
    Cubcrafters Avionics

  3. #3
    Senior Member TroyBranch's Avatar
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    Default Re: G3x horizon malfunctioned

    There is no red X or any sign of an issue if you were IFR which is really scary. Can't fly the cub IFR but in the smokey weather with pour vis the horizon makes flying uncomfortable. I often fly at night and that would be equally uncomfortable.
    This just started on the last two flights. The compass seams to adjust it self every now and again too. So I loose the wind indicator. No issues on the ground when static. Like I had said, it corrects itself after a few minutes while in flight. I can update the software but it should never do this. My RV10 has never done anything like this in 900hrs, it is a different brand.


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    Default Re: G3x horizon malfunctioned

    Just wondered if you were seeing any other signs of error. The compass issue is interesting, since the heading data comes from the magnetometer and all of the other airdata is from the GSU. No red x issues of heading, no magnetic anomaly error messages there either?

    You might consider seeing if there are error in the error log, though I do not know the parameters for the system to log and track them...especially something intermittent. If there are errors in the log you could send them to Garmin for examination.

    My first hunch was that the GSU has a fault, which is not unheard of but we have had very very few issues with them as far as getting bad units out of the box. The magnetometer is more critical in regards to environmental issues - too much ferrous metal nearby, wiring that is too close, that sort of thing. Those usually show up with error messages because you cant correct that with a compass swing.

    Agreed that it shouldnt happen, the hardware behind most of these systems is far more similar than most people realize and most of these systems have very similar requirements for mounting the hardware, they have been pretty well shaken out by now and have proven themselves. Agreed also that software should not affect this, though Ive seen more than one case of random anomalies coming and going just as quickly as they came on.

    Mike Sutton
    Cubcrafters Avionics

  5. #5
    Senior Member TroyBranch's Avatar
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    Default Re: G3x horizon malfunctioned

    No red x, the heading will go yellow just before it re adjusts itself in flight . The horizon gives no indication there is an issue.

    I will figure out how to check the logs. Strange that over a year of solid operation then these strange things happen.

    Thanks for the help.


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  6. #6
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    Default Re: G3x horizon malfunctioned

    Glad to do it, Ive seen the occasional yellow highlighting around heading before, usually will correct with a compass swing. I believe Garmin recommends a swing at some interval...2 years or so, its in the manual, cant recall the exact timing offhand. One last thing, and its what us avionics guys do early on before spending time chasing the invisible, check the connectors. The GSU is canbus data, and in some cases a backup line of rs232 data to the system, and there is rs232 and rs485 data from the magnetometer to the gsu, so its worth a try. I dont find too many problems with pins and sockets but for the time it takes to check them, its easy. If you end up talking to Garmin, they will want to know as much of the factual stuff as you can give them and what you did to check or correct it.

    Mike Sutton
    Cubcrafters Avionics

  7. #7
    Senior Member Jon Delamarter's Avatar
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    Default Re: G3x horizon malfunctioned

    I sent a link to this thread to Garmin G3X support. This is the response:

    Hi Jon,

    Was the “pitch/roll offset” procedure performed in this aircraft? That would be the first thing to perform.

    Next I would run the “engine run-up vibration” test. This will tell you if the ADAHRS is being exposed to excessive vibration.

    http://static.garmin.com/pumac/190-01115-01_AB.pdf

    Mike Huff
    Field Service Engineer
    Experimental Aviation Support
    1200 E. 151st Street
    Olathe, KS 66062, USA
    Phone: +1.866-854-8433
    Jon Delamarter
    Customer Support Manager
    Cub Crafters, Inc.
    jond@cubcrafters.com
    Office (509)367-5200
    Cell (509)833-6993

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