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  #1  
Old 02-17-2021, 01:33 PM
datsclark datsclark is offline
 
Join Date: Sep 2007
Location: Redwood City, CA
Posts: 92
Default Dual GSU 25 - thoughts on this install.

Wanted to ask those of you who've gone before me with GSU 25s about my installation plan. From the g3x install manual this looks like legit orientations, and there should be enough room for 90 Degree Banjo fittings on the top one.

Any issues with mounting on the vans ADAHRS tray like this:



I guess one downside is if i have to remove one for and maintenance the other comes with it.
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  #2  
Old 02-17-2021, 02:05 PM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
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It's clever to be sure, well done!

Hopefully this doesn't start a primer war, but the question I have is "What problem are you trying to solve?"

Are you planning on redundant/independent power to each GSU 25? How about redundant magnetometers, temperature probe, pitot and static? If you run through all the branches of the GSU 25 fault tree, you'll need to address these as well.

I considered the arguments for a back-up ADHARS. But, there was the additional complexity and failure modes, cost, weight, and I just couldn't get there with my installation.

Maybe a G5 + GSU25/G3X would be ok, since it is a different unit (SW/HW), so the likelihood of the same failure mode taking out the back-up is reduced.


"...only flying to Denver..."
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  #3  
Old 02-17-2021, 02:05 PM
rapid_ascent rapid_ascent is offline
 
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Location: Dublin, CA
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It seems like your plan should work. I have 2, but I mounted them side by side. The tubing and the CAN Bus cabling need to loop between them either way you go.

I'm not sure I like the idea of having to take both of them off if one needs to come off in your setup but hopefully that isn't too often. Otherwise it seems fine.
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  #4  
Old 02-17-2021, 02:20 PM
datsclark datsclark is offline
 
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Thanks for the input!

The reasoning is that if one is bricked for any reason, or if the data feed is inop, the other will continue to send data. For such a critical component of the whole system the cost to add that redundancy is minimal. Though I agree -- power or other pitot issues aren't addressed.
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  #5  
Old 02-17-2021, 02:49 PM
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g3xpert g3xpert is offline
 
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Default Backup ADAHRS

Quote:
Originally Posted by datsclark View Post
Thanks for the input!

The reasoning is that if one is bricked for any reason, or if the data feed is inop, the other will continue to send data. For such a critical component of the whole system the cost to add that redundancy is minimal. Though I agree -- power or other pitot issues aren't addressed.
The G5 is a great solution for added redundancy in the G3X Touch system. If you were to lose a GSU 25C, the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically. Also, if you were to have a more wide ranging electrical system failure, a G5 with its attached backup battery will serve as a standalone backup instrument, drawing on its own internal ADAHRS components, GPS receiver and power source to continue operation.

A secondary GSU 25C will also provide a similar additional layer of protection against component failure, without the added benefit of a backup battery connected directly to it.

As long as there is clearance for the connectors, and the bracket is rigidly mounted to the airframe there should not be a problem. It is important not to introduce any unnecessary vibration to the unit(s), so that is just one thing to be mindful of when installing these.

Let us know if you have any other questions.

You can always reach out to our field support group at 1-866-854-8433, or G3Xpert@Garmin.com as well if you would like.

Thanks,

Justin
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  #6  
Old 02-17-2021, 03:04 PM
datsclark datsclark is offline
 
Join Date: Sep 2007
Location: Redwood City, CA
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Quote:
Originally Posted by g3xpert View Post
The G5 is a great solution for added redundancy in the G3X Touch system. If you were to lose a GSU 25C, the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically. Also, if you were to have a more wide ranging electrical system failure, a G5 with its attached backup battery will serve as a standalone backup instrument, drawing on its own internal ADAHRS components, GPS receiver and power source to continue operation.

A secondary GSU 25C will also provide a similar additional layer of protection against component failure, without the added benefit of a backup battery connected directly to it.

As long as there is clearance for the connectors, and the bracket is rigidly mounted to the airframe there should not be a problem. It is important not to introduce any unnecessary vibration to the unit(s), so that is just one thing to be mindful of when installing these.

Let us know if you have any other questions.

You can always reach out to our field support group at 1-866-854-8433, or G3Xpert@Garmin.com as well if you would like.

Thanks,

Justin

Thanks Justin!

I have a G5 going in as well. I had been thinking about the G5 as a stand-alone backup system. It does seem the 2nd GSU is not entirely necessary for redundancy, but can't hurt.
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  #7  
Old 02-17-2021, 03:15 PM
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g3xpert g3xpert is offline
 
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Default G3X Touch/G5 ADAHRS

Quote:
Originally Posted by datsclark View Post
Thanks Justin!

I have a G5 going in as well. I had been thinking about the G5 as a stand-alone backup system. It does seem the 2nd GSU is not entirely necessary for redundancy, but can't hurt.
Yes you will be well covered. Using 3 independent ADAHRS, one thing to keep in mind is that you will want to calibrate the Pitch/Roll offset on all 3 at the same time. Not necessarily simultaneously, but in succession without moving the aircraft. If you were to ever service one of them, and re-calibrate the Pitch/Roll offset, you would again want to re-calibrate all 3 units.

Thanks,

Justin
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