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Garmin G3X Touch - GMU 22 mounting


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I am looking to put a G3X Touch in an RV-8A I am planning to build now. The installation manual shows a mounting bracket for 7 and 9, but nothing for the 8. There are a lot of restrictions on where the Magnatometer can go per the manual. Has anyone been down this road and knows the solution?


John, the manual shows it in the rear deck For the 7-9 models. That is what I did. I remember seeing one mounted on a small shelf bracket just in front of the deck at the top of the fuselage. That may even be a better location than on the deck.
The manual makes it sound almost impossible to meet all the requirements. So, you didn't have any trouble then?
On a shelf in the rear fuse, forward of the horiz. stab.

Mark Navratil, who built a stunning classic 8A, engineered a small shelf under the turtle deck just forward of the station where the horizontal stabilizer attaches to the fuselage. He told me that his works fine there. He was kind enough to send me drawings and photos.

I am attending SNF, but when I return home, I will try to dig up the photos and drawings for you. In the alternative, you could PM him. He is a great guy.
My GMU22 is on a shelf I added just aft of the rear baggage compartment. It met the test specifications there.

It is perhaps a bit close (according to documentation) to the pitch servo which is below and slightly forward of the GMU but it does pass the various tests.

Note: I do not have the aft battery setup that is common for those dealing with CG from heavy noses.

Yes we just did this a couple of weeks ago, getting ready for a full Garmin system install. We found that it was not that hard to put it out on the wing-tip rib, just like Garmin spoke to in the installation manual. We made a small bracket out of two flat plats and a run of 3/4" angle. I think we used .050 plate and .063 angle. We just cut the plates to size about 3/4" to 1" wider than the GMU and the one that mounted to the outside of the tip-rib was cut to fit a spot midway between the spar and the trailing edge of the wing body. Put the aircraft in the level plane and rivet it all together with number 4's along with two knee braces or "struts" if you like and you are done.
Yes I know it did take all of two days and then a little to get it where it was like factory new looking. OH and we put it on with all brass hardware, even the mount to the rib was brass screws and nuts. I do not do pictures well on this site, but if you wish and are willing to let me get back to you as I can send me a PM and I may have a JPG. or two to send you. Hope this helps. Yours as always. R.E.A. III #80888

I have installed the G3X system in my previous RV-8 and will install again in the current -8 in construction.
Here is a pic of the GMU platform I used on both projects.

It is located forward of the 809 bulkhead. This allows for access through the aft baggage area, and I felt came the closest to meeting the separation recommendations in the G3X install manual. This pic shows the platform riveted in place I have also used Brass machine screws to mount as well.
I found there was no way to meet the separation recommendations in the manual. There is simply not enough real-estate in an RV-8. This applies to other components as well, ie COMM/Xponder antenna separation, and remote transponder placement.
During post install setup there was minimal compass error, 1-2 degrees in any quadrant, with all lights and equipment powered.
Both COMMs worked very well with no RF background interference.
I have other pix available.
Mine is mounted in the left wing tip, just forward of the conduit. I used Garmin's universal mounting bracket. I am still in the middle of my avionics / electrical system upgrade, so I cannot report its functionality, but the Dynon mag was mounted in the same wingtip, closer to the leading edge. I'll look for some photos and update this post.

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I also installed a D6 as a backup. At the time Garmin did not offer the dual ADHAR for the G3X. So the Dynon D6 offered redundancy with its own internal standby power. The Magnetometer is wing tip mounted and works very well. Dynon did not seem as threatened by wiring and light fixtures in close proximity. I used LED NAV/STROBE lighting which has a very low power draw.
The item that messed with the D6 magnetometer was the landing lights. They are 55W projection fixtures. Still the induced error was only 2-3 degrees.