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Garmin GI-275 and Other Glass Panel Devices


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This week's Lesson from Tom Turner might interest all who have installed, or are contemplating new glass.  Mooney driver gets in trouble because he doesn't understand all the interconnects and failure modes.  If the upload gets approved, you should be able to download it at

 

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16 minutes ago, Fly Boomer said:

This week's Lesson from Tom Turner might interest all who have installed, or are contemplating new glass.  Mooney driver gets in trouble because he doesn't understand all the interconnects and failure modes.  If the upload gets approved, you should be able to download it at

 

This video doesn't seem to be working - it says "Sorry, we can't show this content because you do not have permission to see it."

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50 minutes ago, Fly Boomer said:

When I get that, it's usually because I'm not logged in.  It also could be that the content hasn't been approved by the admin yet.

And BTW, it's not a video --  it's a PDF of Tom Turner's weekly email blast.

Not sure..  I haven't seen this particular error message before.  

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6 hours ago, Fly Boomer said:

This week's Lesson from Tom Turner might interest all who have installed, or are contemplating new glass.  Mooney driver gets in trouble because he doesn't understand all the interconnects and failure modes.  If the upload gets approved, you should be able to download it at

 

Thanks, Fly Boomer. As someone who is about to get dual GI275s installed, I can say that this definitely got my attention. That pilot had quite a ride. It's amazing and fortunate that he lived to tell the tale.

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Much has been written about this here on Mooneyspace.  This report did have much of the information available but might need some further interpretation on some details.  

When a unit is configured as a primary HSI and a fault occurs with an interconnected unit, it will not automatically switch to reversionary operation mode. In addition, the pilot cannot manually select the ADI display page because it is not one of the pages available when the unit is configured as a primary HSI. Pages available for a primary HSI configuration are HSI and HSI Map; pages available for standby ADI and standby HSI include an ADI page. In July 2020 the directional gyro was removed and a Garmin GI 275 MFI was installed. This MFI was configured as a primary HSI. In October 2020 the attitude indicator was removed and a second Garmin GI 275 MFI was installed, configured as a primary ADI. Because both of these instruments were configured as primary units, a reversionary switch was not installed, nor was it required to be.

Note that the directional gyro was replaced with 275 set up as a primary HSI.  Months later, the attitude indicator was replaced by a second 275 set up as an ADI.  Unfortunately the shop did not change the set up of the HSI to an ADI/standby HSI.  No revisionary mode. The shop should be ashamed of not demanding this change.  Since there was no backup for the ADI, standby instruments were required and in place.  Apparently the owner and the pilot, neither ever checked to see if the HSI switched to display as an ADI.  Shame on them.  The airplane had standby instruments; airspeed, altimeter, turn co-ordinator, VSI, compass, yet the ATP rated and current pilot lost control of the airplane several times.  Airspeeds as high as 70 knots over Vne!

Not only did the ADI enter realignment for some unknown reason, the HSI Xed out also.  What was up with that?  Communication with the Canadian investigator revealed the HSI ADHRS reference was set to ADHRS 1 in the ADI, not ADHRS 2 in the HSI.  When the ADI went, the HSI went too.  Shop? Owner? Pilot? This is operator selectable.  Read about this, it is in the Pilot Guide and the AFM Supplement.

I have two 275s in my panel in addition to my backup airspeed, altimeter and turn co-ordinator.  This failure stuff is scary. However, my 275s have been well behaved and I have read everything available to me about how they are set up and work. I have had another brand display undergo an in-flight realignment.

If considering electronic displays, you must have a fair understanding of how they work.  If you don't want to read thru the Pilot Guide and AFM Supplement give serious consideration to sticking with the steam gauges.  Even those, about once a month here on MS, someone writes their attitude indicator and directional gyro have both quit working on the same flight.  What could it be?   Even old technology is not immune to ignorance.

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11 hours ago, Fly Boomer said:

he doesn't understand all the interconnects and failure modes

When my plane comes back to me, I intend to fly (VFR) with another pilot who will pull each breaker one at a time while I am under the hood, and also to turn off the master switch. 

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I found this harrowing just to read. After a year of having a GI 275 ADI installed, it's been perfect, and I hope for it to always be that way. My partners and I are now talking about a second unit for the HSI and we are well aware that there is additional wiring and expense in making the two reversionary.

Lastly, I'm not aware of, nor was I able to find, a GI 275 training app as mentioned in the article.

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I don’t think it is fair to blame the shop. Garmin makes a lot of equipment that can be installed in a myriad of configurations. The owner really has to figure out what they want and design an installation with the installer that meets those requirements. And, a pilot flying one of these airplanes needs to fully understand the capabilities and limitations of a particular installation rather than assuming it functions the same as a similar installation in another airplane.

This stuff is complicated when you dive below the surface. For instance, who would guess that loss of GPS would screw up a coupled ILS approach in your fancy new GFC 500?

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2 hours ago, Fly Boomer said:

Pretty sure @PT20J went through the process of testing every potential failure mode with his new toys.

Yes, and that's the kind of pilot I want to emulate!  Really appreciate the fact that not only did he do this, he's posted extensively about it here on Mooneyspace.  Incredibly valuable, many thanks to @PT20J.

One thing I'd strongly encourage all instrument pilots to do is to go up with a safety pilot under the hood, and fail every gizmo in your airplane you can, in every way you can think of.  You're extremely unlikely to damage anything, and extremely likely to learn something.

In my case, my position as a hobby CFI at the local flight school affords me a lot of opportunity on this front.  Every single airplane at that school has dual G5s and a GFC-500 autopilot (I'm amazed at this, all the airplanes are 70s-era birds, but somehow the owner is able to keep the interiors and panels in nice shape).  When flying with instrument students, I power down devices, pull breakers, etc.  In theory I'm the old sage, but I'm always honest with the student that it's sometimes a learning experience for me too.  The other day I shut down the upper G5 (ADI) in an airplane, and left the lower G5 (HSI) running.  After a few seconds, the lower G5 auto-switched to become an ADI as expected, and I let the student struggle with that (if you haven't done this, do it on your next flight - it's much more distracting than you would think).  When I finally took pity on the student and turned the upper G5 back on, the lower G5 did *not* auto-switch back to an HSI, but had to be manually switched back.  I made a mental note about what this would mean in a failure mode where the primary G5 has a problem that causes it to intermittently lose and re-gain power.

For people that fly multiple airplanes, note that the behavior in one airplane won't necessarily follow to another airplane, even if it has the same equipment.  As has already been stated here, modern avionics have a number of software config options that control behavior.  The one I run across most frequently is whether an IFR-certified, combination GPS/VLOC navigator, is set to auto-switch from GPS to VLOC mode when transitioning from enroute navigation to a ground-based instrument approach.  This is software configurable, at least in the Garmin GTN series navigators.  The GTN in my airplane auto-switches, but the one in the flight school airplane doesn't.  I've seen at least one internet fight where the participants got into a giant argument about this, neither one of them understanding that it's configurable in software.

More generally, I just can't emphasize enough how important it is to actually train with whatever "redundancy" you're proud of in your airplane.  I can't tell you how many times I've asked pilots - on forums and in real life - if they've actually tried to shoot an instrument approach with the redundant system they're so proud of.  e.g. getting attitude information from a backup indicator.  Or more interestingly, on an iPad from the AHRS in their GTX 345 or Sentry or BOM or whatever.  Disturbingly often, the answer is.... crickets.  A significant portion of the pilot population has this surprising attitude that they'll just be able to figure out - literally on-the-fly - how to use their backup system when the chips are down.  :wacko:

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35 minutes ago, Vance Harral said:

Yes, and that's the kind of pilot I want to emulate!  Really appreciate the fact that not only did he do this, he's posted extensively about it here on Mooneyspace.  Incredibly valuable, many thanks to @PT20J.

One thing I'd strongly encourage all instrument pilots to do is to go up with a safety pilot under the hood, and fail every gizmo in your airplane you can, in every way you can think of.  You're extremely unlikely to damage anything, and extremely likely to learn something.

In my case, my position as a hobby CFI at the local flight school affords me a lot of opportunity on this front.  Every single airplane at that school has dual G5s and a GFC-500 autopilot (I'm amazed at this, all the airplanes are 70s-era birds, but somehow the owner is able to keep the interiors and panels in nice shape).  When flying with instrument students, I power down devices, pull breakers, etc.  In theory I'm the old sage, but I'm always honest with the student that it's sometimes a learning experience for me too.  The other day I shut down the upper G5 (ADI) in an airplane, and left the lower G5 (HSI) running.  After a few seconds, the lower G5 auto-switched to become an ADI as expected, and I let the student struggle with that (if you haven't done this, do it on your next flight - it's much more distracting than you would think).  When I finally took pity on the student and turned the upper G5 back on, the lower G5 did *not* auto-switch back to an HSI, but had to be manually switched back.  I made a mental note about what this would mean in a failure mode where the primary G5 has a problem that causes it to intermittently lose and re-gain power.

For people that fly multiple airplanes, note that the behavior in one airplane won't necessarily follow to another airplane, even if it has the same equipment.  As has already been stated here, modern avionics have a number of software config options that control behavior.  The one I run across most frequently is whether an IFR-certified, combination GPS/VLOC navigator, is set to auto-switch from GPS to VLOC mode when transitioning from enroute navigation to a ground-based instrument approach.  This is software configurable, at least in the Garmin GTN series navigators.  The GTN in my airplane auto-switches, but the one in the flight school airplane doesn't.  I've seen at least one internet fight where the participants got into a giant argument about this, neither one of them understanding that it's configurable in software.

More generally, I just can't emphasize enough how important it is to actually train with whatever "redundancy" you're proud of in your airplane.  I can't tell you how many times I've asked pilots - on forums and in real life - if they've actually tried to shoot an instrument approach with the redundant system they're so proud of.  e.g. getting attitude information from a backup indicator.  Or more interestingly, on an iPad from the AHRS in their GTX 345 or Sentry or BOM or whatever.  Disturbingly often, the answer is.... crickets.  A significant portion of the pilot population has this surprising attitude that they'll just be able to figure out - literally on-the-fly - how to use their backup system when the chips are down.  :wacko:

The first time I tried flying the GTX 345 AHRS with my iPad (before the new G3X panel) I found it impossible. Turned out the AHRS was bad. Even after the warranty exchange, it was never great and would drift in pitch, especially in turns.  With the G3X STC it is disabled and the GTX uses the GSU 25 ADAHRS data from the G3X. Probably Garmin knows the GTX AHRS us a toy.

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4 hours ago, PT20J said:

The first time I tried flying the GTX 345 AHRS with my iPad (before the new G3X panel) I found it impossible. Turned out the AHRS was bad. Even after the warranty exchange, it was never great and would drift in pitch, especially in turns.  With the G3X STC it is disabled and the GTX uses the GSU 25 ADAHRS data from the G3X. Probably Garmin knows the GTX AHRS us a toy.

Yeah, I've tried flying under the hood using our GTX AHRS driving Foreflight's PFD feature, and had similar experiences - though not quite as bad as you report.

One thing I learned from doing so, like many others, is that the GTX AHRS just doesn't seem to be that good.  In my airplane, it's good enough to keep the greasy side down; but the AHRS itself - or the bluetooth connection between it and the iPad - lags.  And the system indicates a few degrees of pitch or bank when the certified attitude indicator (and the view out the window) show straight and level.  At my current level of proficiency, I'm actually a little better with with classic partial panel ASI/TC/ALT/VSI than I am with the iPad/GTX as a backup attitude source.  I think if I practiced more, I could adapt my brain to deal with the minor lag and inaccuracy in the iPad/GTX system and perform better than classic partial panel with the remaining mechanical instruments.  That would require more training, but honestly that's not a big knock against using the iPad/GTX as backup - its peculiarities are no worse than classic partial panel.  At this point I like to think I could use either strategy, but in the event of an actual attitude indicator loss, my current plan is to stick with classic partial panel.  That will probably change when we get our second G5 installed here in a month or so.

The more interesting lesson for me using the iPad/GTX was a user interface issue, rather than anything "incorrect" about the system.  Foreflight's PFD feature employs synthetic vision, and paints terrain, airports, traffic, etc. in its depiction of the "background" behind the attitude indication.  This matches what folks with big screen Garmin and Dynon systems enjoy.  But if you're used to looking at a small, "classic" attitude indicator without synthetic vision, this turns out to be a little disorienting at first.  The reason is that a basic attitude indicator - whether mechanical or electronic - shows a static picture when your attitude is not changing.  In other words, nothing on the display "moves" if you're straight and level, or in a constant rate turn.  With the addition of synthetic vision, the background moves even when your attitude is not changing.  Terrain features slide horizontally in a turn.  Even during straight-and-level flight, airports and other ground features slide down on the display as you tool along, due to them passing beneath you.  There is nothing incorrect about this functionality, but it's hella disorienting if you're not used to it.  With a little practice, I was able to effectively tune it out (perhaps I should say tune it "in").  But again, not something I'd be wanting to deal with for the first time during an actual attitude indicator failure in IMC.

We're fortunate to have lots of options for backup attitude in the modern era, whether certified or "advisory".  All of them can help if you train with them.  If you don't, all of them can burn you worse than if you never had them in the first place.

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