Garmin G5 attitude indicator or HSI

Discussion in 'Avionics and Upgrades' started by jd21476, Oct 13, 2020.

  1. jd21476

    jd21476 Pre-takeoff checklist

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    Is there a difference between the G5 that replaces the Attitude Indicator and the one that does the DG/HSI? I thought you could select which one you want when you buy it and the G5 does either, correct?
     
  2. bnt83

    bnt83 Final Approach PoA Supporter

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    The actual display you look at are identical part numbers.

    The DG/HSI kits contain additional equipment that enable those functions.

    Example. To get magnetic heading you need a GMU11

    To get navigation radio displays you may need the GAD29B depending on what radios are going to be interfaced.

    Seems like the minimum requirement is one standby battery on the attitude, but optional is installing them on all G5 displays.
     
    Last edited: Oct 13, 2020
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  3. jd21476

    jd21476 Pre-takeoff checklist

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    So when I look at a site like Aircraft Spruce I can see three different G5 prices. Which one do I need so that it will connect to my Garmin GNC355 and work as a DG/HSI?
     
  4. bnt83

    bnt83 Final Approach PoA Supporter

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    The expensive one that includes the G5, GMU11 and GAD29B.

    (Unless you already have a GMU11 installed that may have been installed as an option with a G5 in the attitude indicator position)
     
  5. jd21476

    jd21476 Pre-takeoff checklist

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    Well, that figures
     
  6. chemgeek

    chemgeek Pattern Altitude

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    You need the G5 HSI with the GMU-11. If you want to interface with an autopilot, you need both the GMU-11 and GAD29B.
     
  7. bnt83

    bnt83 Final Approach PoA Supporter

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    Get get HSI the GAD is required in this case, autopilot or not.
     
  8. jd21476

    jd21476 Pre-takeoff checklist

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    I dont have autopilot so it wont be an issue but sounds like I needs the expensive one anyway
     
  9. David Megginson

    David Megginson Pre-takeoff checklist

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    The nice thing about the expensive one with the remote magnetometer is that you won't have to continually update it to match your mag compass, like you do with a mechanical DG.
     
  10. EdFred

    EdFred Taxi to Parking

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    And it automatically dials in the new course for you when changing waypoints.
     
  11. jd21476

    jd21476 Pre-takeoff checklist

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    But if I find a used Attitude Indicator I could buy it and then just purchase the GMU11 and GAD29B separate, correct?
     
  12. bradg33

    bradg33 Pattern Altitude

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    You're likely to find that won't be economical. Word is Garmin is charging ~$799 for the STC permission letter that you'll need for a used unit.
     
  13. MacFly

    MacFly Pre-takeoff checklist

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    I believe that the STC'd version require two display heads. On mine, I can toggle between DG and HSI, but it's the Experimental version. Heading and autopilot are part of the EFIS so I skipped the GMU and GAD. The G5 is pretty much just backup.
     
  14. EdFred

    EdFred Taxi to Parking

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    Certified can also toggle between AI and HSI if you have the appropriate ancillary equipment.
     
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  15. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    Just to be clear, STC vs experimental are the same hardware (for the G5 itself, the GMU11 and GAD29B have PMA'd and non-PMA'd variants), so is the software. It's all just configuration options. When installing the "certified" way, you select the installation type to "certified instrument" which disables some of the stuff that the experimental are allowed to do (like the large HSI) and when installing as an AI per STC you have to disable the switching between AI and HSI on the G5 installed as an AI. The HSI is configured to boot as an HSI, but can be switched to AI at any time and will automatically switch to an AI if you turn off the AI in a dual G5 install, when installed as just an HSI and you keep your vacuum AI, it's nice that you can revert the HSI to AI if your vacuum AI goes TU. There is no difference between a G5 you buy as an AI vs HSI, other than what other hardware comes in the kit. AI comes alone, HSI comes either with GMU11 or with a GMU11 and GAD29B. You could buy the AI kit, later decide to install something else for an AI and move the G5 to HSI, and add the GMU11 and GAD29B and change the config and poof, it's now an HSI... there would be no need to buy the "right" G5.
     
  16. EdFred

    EdFred Taxi to Parking

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    I thought (I'll try again next time out to the hangar) that I could switch both the G5s between AI and HSI. Or is the disabling the HSI on the AI not required for a dual installation?
     
  17. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    If you can switch your AI to an HSI, it's not configured as per the STC install manual, whether it's a single or a dual. In a certified install only the HSI is allowed to switch. It's a very common thing to overlook (and effectively harmless, but not "proper").

    Screen Shot 2020-10-15 at 3.38.51 PM.png
     
  18. chemgeek

    chemgeek Pattern Altitude

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    On the certified AI install, you also not allowed to manually adjust the AI pitch indicator up or down. It must be installed so that zero degrees pitch is achieved when the aircraft is leveled on the ground, and the manual adjustment disabled. This requires a bit of adjustment in setting pitch/power combinations for instrument flight.
     
  19. jd21476

    jd21476 Pre-takeoff checklist

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    So I still need the expensive G5 even though I am connecting it to my Garmin GNC355? It still needs the GMU11 and GAD29B, correct?
     
  20. David Megginson

    David Megginson Pre-takeoff checklist

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    The GAD29 gives you ARINC 429 support — that's what lets the G5 act as an HSI (including lateral and vertical course deviation) rather than just a DG, and allows the GFC 500 to follow a flight plan from your GPS or to fly an approach. Without that, the GFC 500 wouldn't be very useful except for holding a heading or altitude.

    The GMU11 would save you from having to manually adjust the G5 to match the mag compass periodically. I don't know if the GFC 500 requires it or not, but it does appear to be required to use the G5 as the primary CDI for VHF (VOR or LOC) navigation.
     
  21. jd21476

    jd21476 Pre-takeoff checklist

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    So I dont have autopilot and I was told by a friend that I would only need the GMU11 and not the GAD29. He said the GAD29 is more for those with Autopilot
     
  22. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    As David mentioned, the GAD29/GAD29B is for ARINC 429 support, it's essentially an ARINC 429<->CANBUS converter. The B variant is only needed when interfacing with a third party autopilot, however Garmin unfortunately stopped making/selling the PMA'd GAD29 (which was a few hundred cheaper than the GAD29B), so the only one you can buy these days is the GAD29B. It is required if you want to use the G5 as an HSI with the GNC355. You'll run RS232 from the GNC355 for MapMX (GPS data source) to the G5s, and an ARINC 429 in and and out from the GNC355 to the GAD29B. So yes, if you want to display CDI/VDI on the G5 from the GNC355, you need the more expensive kit that includes the G5, the GMU11 and the GAD29B.
     
  23. asicer

    asicer Final Approach

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    If you do that then there's no way to get lateral/vertical guidance from the GNC355 to the G5 and no way to get heading from the G5 to the GNC355.

    Edit: @Ryan Klems was 625 milliseconds faster on the "post" button than me :)
     
  24. David Megginson

    David Megginson Pre-takeoff checklist

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    I have a vague recollection that, unlike the G5, the GI-275 does not require the GAD29(B) to get lateral and vertical course info from the GPS navigator. Can anyone confirm? That would make the price difference a little less painful (save $500-650), and it's a much nicer unit.
     
  25. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    That's correct. In fact, it can even work with analog NAV signals, which you can't do with the G5 through any means.
     
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  26. EdFred

    EdFred Taxi to Parking

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    Well I guess the plane isn't airworthy, can set either one to HSI or AI mode.
     
  27. hindsight2020

    hindsight2020 En-Route

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    Don't worry man, your secret's safe with us.
    [​IMG]
     
  28. jd21476

    jd21476 Pre-takeoff checklist

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    What about the Uavionix AV-30C? Has anyone used it or looked in to it? Can it be used as a DG/HSI?
     
  29. chemgeek

    chemgeek Pattern Altitude

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    The AV-30C can display DG or HSI mode using GPS input, but it is not slaved to a magnetometer like the G5. Having the GMU-11 is a huge benefit. One less thing to deal with in flight.
     
  30. Ryan Klems

    Ryan Klems Pre-takeoff checklist

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    I think uavionix’s description of it as an HSI is a bit disingenuous IMHO. It cannot replace a CDI (at least for IFR... while it gives some CDI like indications, it’s not approved for that), and it can’t give any sort VDI indications. So you are still stuck installing a CDI. I’m looking forward to what it might become down the line, but other than as an attitude indicator right now, just feels very limited.