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Placement of GSU 25 ADAHRS?

GSU25 Mounting

Make sure you read the G3X installation manual. It lists requirements for mounting of all the various LRUs. Section 16.4.1 specifically says the wing is not a good place to mount the GSU25. It must be mounted in a very rigid location. They don't recommend it mounted to the back of the display either because of possible flexing of the instrument panel! It is very sensitive to vibration. Download the manual from the Garmin website for the exact verbiage.

I am mounting mine behind the baggage aft wall near the top skin on a plate. This is a very rigid location that also keeps the lines from the pitot from having to pass through the spar.
 
Mounting GSU25 to the back of the GDU display

Make sure you read the G3X installation manual. It lists requirements for mounting of all the various LRUs. Section 16.4.1 specifically says the wing is not a good place to mount the GSU25. It must be mounted in a very rigid location. They don't recommend it mounted to the back of the display either because of possible flexing of the instrument panel! It is very sensitive to vibration. Download the manual from the Garmin website for the exact verbiage.

I think there were some vibration issues with the GSUs mounted on the displays in the RV-12. The -14 probably has a stiffer panel structure than the -12. I noticed at Oshkosh this year that Mitch Lock has the GSU25s mounted on the back of the GDU displays in the panel of the -14A demo plane. He told me the AHRS and autopilot performance have been rock solid with no issues. This does require running the pitot, static, and AOA tubes up to the panel but on the other hand it makes the wiring very simple.

IMHO the biggest downside to mounting GSUs on the back of the displays is that when you want to remove a display you have to either disconnect the lines or else unbolt the GSU. Quick disconnects on the pitot/static/AOA lines would be easiest, but you probably increase the risk of introducing a leak every time you remove and install the lines...

YMMV...
 
Make sure you read the G3X installation manual. It lists requirements for mounting of all the various LRUs. Section 16.4.1 specifically says the wing is not a good place to mount the GSU25. It must be mounted in a very rigid location. They don't recommend it mounted to the back of the display either because of possible flexing of the instrument panel! It is very sensitive to vibration. Download the manual from the Garmin website for the exact verbiage.

The guys at g3xpert for Garmin are really helpful. When I built mine, I was torn between the wing mount and behind the panel. Mine is mounted to the back of the PFD and there is no problem. Yes, you will have to run the pitot and AOA lines from the wing up to the back of the panel, but you will also have the static come up there as well. If you use a backup system, you will have to run lines to it as well. I have a GRT Mini in the center of my panel, so the pitot and static both come up the center to a "T" and split off to the Garmin and the GRT and the Garmin also has the AOA.

Spoke to both Van's, Garmin & Aerotronics (who built my panel) and it was agreed that it would work there. I am not familiar with the 12, but my panel doesn't get a lot of vibration and even less since I had my prop balanced. I didn't realize there was any vibration, but once I get it balanced, it's like "butta". Really smooth running now. I would absolutely put it behind the PFD, there is already a place to mount it. Hope that helps.
 
Not flying yet, just wiring up the panel now.

I chose to put it on the back of the display. This is convenient for hooking up the G5 which is in the center stack.

I don't see much difference in running the pitot/AOA lines through the spar as opposed to running them aft. With both devices that need pitot/static in the panel it is easy to hook them up together.

Removing the GSU from the back of the display also doesn't seem like much of a problem.
 
As Mark said, I have dual GSU25s mounted to the back of the PFD and MFD. Have been working flawlessly since first flight.
 
Hello,

Just don't forget that those big 10.6" GDU 460 displays create large access holes in the panel each time you want to remove one and gain access to devices or wiring mounted behind the panel.

Just remove 4 cap screws and out they come - but wait, the pitot/AOA/static lines are now attached to the ADAHRS on the back of the display because I didn't remote mount my ADAHRS units! Drat!

Just saying...

Steve
 
As Steve says, the screens make awesome access panels for the subpanel area. I mount absolutely as much as I possibly can on the cub panel.
 
Hello,

Just don't forget that those big 10.6" GDU 460 displays create large access holes in the panel each time you want to remove one and gain access to devices or wiring mounted behind the panel.

Just remove 4 cap screws and out they come - but wait, the pitot/AOA/static lines are now attached to the ADAHRS on the back of the display because I didn't remote mount my ADAHRS units! Drat!

Just saying...

Steve

Yes Steve, but with a tipup canopy, it's easy breazy to remove the lines going to the ADAHRS from above. I really don't see a need so far to pull the screen unless IT had to be serviced. Just my opinion.
 
Not only is it easy to get at with the tip up canopy, the most surprising thing about the 14 is how little space for mounting there is on the subpanel. The radio stack is already reduced in size for items in trays because of the canopy lift mechanism. (No complaints about that, it is an elegant solution to removing struts from the side entry.)

A GAD 27 and GEA 24 on the left side, nope, no room for a GSU 25. A GAD 29 and a GDL 39R on the right side, nope, no room for a GSU 25 there either.

If it works on the back of the display unit, it seems like the best place for it. Since it seems to be working for others, that's why mine is there.
 
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