NOT RECIEVING ARINC 429 MESSAGE DUAL G5

Discussion in 'Avionics and Upgrades' started by Davisando, Jul 7, 2020.

  1. Davisando

    Davisando Filing Flight Plan

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    Hello Everyone!

    I recently upgraded the avionics on a 1979 PA28-181 with dual G5s / GMA 342 / GNX 375 / GNS 255. Everything was fine until a day after a month and a half of the upgrade, when I started to get a fail in the heading data in the PFD G5, followed by a message "Not receiving ARINC 429 data" in the lower G5 HSI. I went back to the avionics company with the issue and they have tried different fixes like cleaning the connections, they changed the GMU, reseted the entire system.. all about 4 different times, but it just comes back. Today they said everything is fine, they think it might be the vibration of the propeller, might be out of balance.... but im not convinced about that. I am really frustrated about this, if anybody can give me a hint of what the problem would be and a possible solution, it would be GREATLY APPRECIATED.... Thank you in advanced!
     
  2. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    So only the HSI is giving the not receiving ARINC 429 data error and only the AI is failing on the heading data? Does this occur on the ground, or only when flying? If you can reproduce this on the ground, it'd be interesting to boot the unit to config mode and see what the CANBUS network error rate is for the devices on the network (should be 0% anything other than that and there is either an intermittent connection for a device, or terminators are not properly installed, etc). Do you have a drawing for the install showing where the various components are and where the terminators are located?
     
  3. Jesse Saint

    Jesse Saint Line Up and Wait

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    Sounds like a problem with the CAN Bus. Heading comes from the GMU11 and ARINC comes from the GAD29. Check in diagnostics for CAN Bus errors.
     
  4. jbDC9

    jbDC9 Pre-takeoff checklist

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    Interesting; I have dual G5s and a GNX 375 in my RV-8... I have the same message displayed on my upper ADI G5. Funny thing though, I don't really notice anything missing with functionality. I'll boot to config mode and check for CAN bus errors as well.
     
  5. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    I'd also check to see what devices your two G5's see on the bus (hopefully all the same ones?). Also check your ARINC 429 settings on the G5. If you are only interfaced with a GNX375 I'd only expect 1 TX and 1 RX to be configured, if you have more than that enabled that could be the source of the message as well.
     
  6. RG3

    RG3 Filing Flight Plan

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    Similar issue here. Dual G5’s, GFC500, garmin 530w. I don’t have the heading issues but will intermittently get “ARINC 429 interface hardware fault” or “ARINC 429 interface power supply fault” and have also gotten “Not receiving ARINC 429 data”, although that one hasn’t happened in quite awhile. These don’t happen on every flight and they usually go away after a few seconds or a few minutes. Similar to a previous post, Never noticed any functionality issues when the messages appear but also have never had it happen while coupled to an approach. My shop replaced the GAD29b (per Garmin recommendation) but the issue returned a couple flights. Thoughts?
     
  7. Davisando

    Davisando Filing Flight Plan

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    Thank you all for the answers. It happens both on the ground and in flight. It comes and goes too... but there were a couple times it stayed the majority of the flight. I will check the "CAN BUS" don't really know what that is. I don't loose functionality from the PFD G5 when I get missing heading, but it boots the PFD from the lower G5 (HSI), so it gets annoying having to switch over and over again back to HSI. I usually load visual approaches and I had one time lost the heading indicator on the PFD G5 while on it. I will boot in configuration mode and update the status of the G5's. I don't know if it is only connected to the 375, I also have the GNS 255 and GMA 342, don't think those have linkage to the G5's thought
     
  8. Davisando

    Davisando Filing Flight Plan

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    I will do that and see what I get, thanks
     
  9. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    That’s pretty definitive that there is a CANBUS fault then. The HSI will revert to AI mode when it stops seeing the AI, this is a safety thing so that if the AI fails you don’t have to do anything to go in to reversionary mode. Something is causing a failure on the CANBUS segmenting the AI and/or HSI from other parts of the system and making it think the AI failed.
     
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  10. Davisando

    Davisando Filing Flight Plan

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    Ok, I will look into it and let you guys know, thanks
     
  11. Nathan Miller

    Nathan Miller Pre-takeoff checklist PoA Supporter

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    Screenshot_20200709-105200_Adobe Acrobat.jpg ARINC is between the GAD 29B and the GNX. The GAD 29B concerts that to CANbus (digital network backbone). Since this is a problem that has developed (vs one that has been with you since the beginning), I'm ruling out a settings/configuration issue. My money would be on poor workmanship. Having personally installed a G5 HSI, GMU 11, GAD 29b and interfacing it to my *groan* dealer installed GNX 375, let me tell you, those pins are a PITA to crimp - you have to have the EXACT length stripped back correctly and crimped precisely. And there are dozens of them. I would suspect a bad crimp on one or more of the ARINC connections (8 pins, in total). CANbus should be fine. It might take some effort to have the shop agree to dig into their installation. They will be opening up a can of worms. But, they installed it and they should stand behind their work.

    Good luck and keep us posted.
     
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  12. Davisando

    Davisando Filing Flight Plan

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    Thats what I am afraid of. I have taken the plane four times and they have "done anything they can" and CAN'T find a solution. It was a very expensive installation and the idea of going to another shop and spending more for somebody else to fix it is frustrating. They should do a "re-install" as I suggested but of course they don't feel like doing it...:(
     
  13. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    While you are correct that the ARINC connections are between the GAD29 and the GNX and GNC, the GAD has to be able to communicate over the bus with the G5s in order for the signal to reach the G5s. You will get the same fault indication for one of the ARINC connections being set to the wrong protocol, being disconnected, or the GAD29 dropping from the bus. And given the other symptoms (AI losing heading, HSI reverting to AI, not seeing the same ARINC message on AI), this is almost guaranteed to be an issue with the CAN bus wiring causing loss of communication between various LRUs.
     
    Last edited: Jul 9, 2020
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