What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Dual GSU 25 - thoughts on this install.

datsclark

Active Member
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:

gsus-X5.jpg


I guess one downside is if i have to remove one for and maintenance the other comes with it.
 
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..."
 
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.
 
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.
 
Backup ADAHRS

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 [email protected] as well if you would like.

Thanks,

Justin
 
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 [email protected] 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.
 
G3X Touch/G5 ADAHRS

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
 
The clearance between the top ADAHRS and the tail cone skin for the static/pitot/AoA lines looks quite tight. Might be worth checking that.
 
Ouch . . . ?

It does seem the 2nd GSU is not entirely necessary for redundancy, but can't hurt.

Functionally maybe not, but . . . there is the cost, plumbing, weight, wiring, and labor & time to install. The G5 might provide all the redundancy desired.


Simplify.
 
If you were to lose a GSU 25C, the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically.
Justin

Sorry for the thread drift here. When I asked this question a few years ago (non-touch system), you indicated that the 25 must be powered down in order for the system to use the G5 ADHRS data. Have you updated the s/w to now support automatic cross fill without powering down the 25? Does this apply to the 370 based systems also?

Larry
 
G5 Crossfill

Sorry for the thread drift here. When I asked this question a few years ago (non-touch system), you indicated that the 25 must be powered down in order for the system to use the G5 ADHRS data. Have you updated the s/w to now support automatic cross fill without powering down the 25? Does this apply to the 370 based systems also?

Larry

Larry,

No it is the same behavior, I could have been more clear. If the GSU 25C were to fail (equivalent to pulling the power on the GSU 25C), the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically.

Thanks,

Justin
 
Larry,

No it is the same behavior, I could have been more clear. If the GSU 25C were to fail (equivalent to pulling the power on the GSU 25C), the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically.

Thanks,

Justin

How is failure of one LRU determined by others on the network? Is there metadata like sensor status, etc. shared by the LRU with other units? Do the other units look for disagreements between sources? Dropped data frames? Total loss of communication?
 
Larry,

No it is the same behavior, I could have been more clear. If the GSU 25C were to fail (equivalent to pulling the power on the GSU 25C), the ADAHRS information from the G5 will be crossfilled to the G3X Touch display automatically.

Thanks,

Justin

So, to be clear, a complete 25 failure will allow auto cross fill, however, erroneous data with an otherwise running 25 requires it to be powered down to gt cross fill from G5?

Larry
 
GSU 25 Monitor

How is failure of one LRU determined by others on the network? Is there metadata like sensor status, etc. shared by the LRU with other units? Do the other units look for disagreements between sources? Dropped data frames? Total loss of communication?

The GSU 25 monitors the health of its on board sensors and if it determines there is an issue, will invalidate its attitude output. In this case, the attitude information from the G5 would be displayed on the G3X Touch PFD.

With multiple GSU 25's installed in a system, the attitude and air data outputs from each ADAHRS LRU are monitored and compared against one another. If a disagreement is found to exist, a CAS message is generated to alert the pilot to the condition.

Thanks,

Justin
 
Back
Top