Can a GI-275 ADI be configured differently than the GI-275 Standby ADI (i.e., ADI page of HSI) in the same plane?

[bkspero]

In my plane I have a pair of GI-275s. One operating as a primary ADI, and the other as what Garmin calls a Standby ADI (it operates as an HSI but will revert to an ADI if the other -275 fails).

The primary ADI is configured as a 3-in-1 instrument so that I can have the miscellaneous fields displayed (OAT, TAS, GS, Wind vectors). I accept that it does not display heading, as that information is available on the HSI.

The ADI page of the Standby ADI was configured by the shop the same way. However, I would prefer to have the Standby ADI configured differently as 4-in-1 instrument because if I am using it as an ADI, then the HSI page is no longer showing and I need the Standby ADI to display heading. I can accept that only one of the miscellaneous fields is displayed in 4-in-1 mode because the value of heading information on that instrument is more important.

The shop doesn't know the answer. They will dig into the manuals and call Garmin to try and find out, but the cash meter will be running while that is happening, and there is no guarantee that this can be done. So before I give them the ok to start this work I was hoping that someone here knows and can share the answer.

What make we concerned that they must be configured the same way is that I just did a minor change to add the CDI display to the primary ADI (this is a user setting) and I found that this setting showed up on the Standby ADI without me configuring it there separately.

 

[flyingcheesehead]

Looking at the install manual, I don't see any reason why they couldn't be configured how you want them. I like the way you're thinking, that config makes a lot of sense to me.

 

[M20K]

It may be because the second 275 is designated as a "Stand By" and the STC for your aircraft requires it to be set up a certain way.

But that's just a guess and the fact that your shop doesn't know really makes me wonder if it is just that they have no clue how to configure it. (So simple answer is, find a new avionics shop.)

 

[WDD]

Have you gone into the configuration mode for the 2nd GI275 and attempted to change it?

To get to the configuration mode, while holding/pushing the GI 275's knob in, turn the power on.

I wouldn't pay your electronics shop to learn how to do this so they can then charge you to do this. This should take about 5 minutes, which includes the time you will spend hunting for the airplane keys you know you always put in the same place in your flight bag but for some reason you put with your car keys by mistake.

 

[bkspero]

Thanks all for your insights. It's interesting that no one so far has set them up the way I would like them. So, while I agree with Flyingcheesehead that there's nothing apparent in the installation manual that says it can't be done, neither is there anything there (at least in the version I looked at) that says it can be done, or how to best do it (eg., with each one powered up separately and the other one off, or with both powered up separately).

 

[Llewtrah381]

Thanks all for your insights. It's interesting that no one so far has set them up the way I would like them

Yes, I have it that way and it’s in the Config page as WDD said.

From my personal notes:

AI: can be Basic, 3-in-1, or 4-in-1. 3-in-1 shows the wind

To change, go into Config mode (press knob while powering up), scroll to Setup, select Airframe Config, select ADI Style, then choose.



Chevron (Flight Director) vs traditional is under Airframe Config as well, just below ADI Style

HTH

 

[Llewtrah381]

I just did a minor change to add the CDI display to the primary ADI (this is a user setting) and I found that this setting showed up on the Standby ADI without me configuring it there separately.

I just caught what I think you said here.

For the Primary to truly be Primary and therefore legal for certification, I don’t think it’s supposed to be able to switch to some other mode - ever. I can clearly see that as a safety feature. So, while I don’t think I’ve played with things as you have, given how the AI and HSI are interconnected, I could see where attempting to change the AI would change the HSI instead.

BTW: I’m not sure how you got “true” CDI as an option, even for the HSI: while my HSI clearly shows all the info the CDI page does (but in a different format), I don’t believe either of my 275s are capable of showing the CDI page available on other 275 models (I tried to make that as an option but couldn’t, IIRC).

Maybe we have different models and/or firmware. Or maybe I’m misunderstanding.

 

[Jon Wilder]

No, it cannot be configured that way.

In a dual GI 275 setup where the HSI doubles as the reversionary standby ADI, the magnetometer is to be interfaced with the GI 275 that is functioning as the primary ADI as per the STC (the primary ADI functioning as the primary heading source to the HSI). As the GI 275 is the magnetometer's power source, the standby battery in the HSI/Standby ADI would not meet the minimum standby time requirement if it were also supplying power to the magnetometer, thus they interface it to the non-standby instrument instead. Therefore, the HSI/standby ADI does not have a valid heading source when operating in reversionary mode where the ADI is inop. Supporting this is the fact that the STC Installation Manual lists the magnetic compass as the standby heading source.