The light at the end of the tunnel…

…is getting brighter – it’s time to start installing and wiring avionics. I’ve been plotting and planning how to mount the Garmin G3x Touch system, radios and transponders and I’ve settled on building a tray which will hold all the remote-mounted LRUs, Comm 2 and transponder.

Here’s a cardboard mockup.

Avionics tray mockup…and the tray with avionics temporarily attached.

Avionics tray fitting 1The GAD 27 and GAD 29 are on the right side. Most of the airframe power interfaces will be through the right firewall passthrough so having these boxes on the right should make wiring a little more straightforward.

GAD 27 and GAD 29The GEA 24 engine interface is on the left side as most of the engine sensor wires will come through the left firewall passthrough. Guess where the AoA CPU is going?

GEA 24More pics? Sure, I’m glad you asked.

The avionics tray from overhead

4 thoughts on “The light at the end of the tunnel…

    • Bjorn,

      The tray is 0.040″ 2024-T3 and the stiffener angles are 0.063″ 6061-T6 angle, 3/4″ legs. Like the two other subpanel support ribs, the center “drop” rib is 0.025″ 2024-T.

      In the interest of full disclosure, I used what I had on the shelf so the the design is a bit of a WAG with regard to structural analysis. But lots of other folks use angle or other material to mount avionics behind the subpanel so I’m not too concerned about loads or margin.

      Hope this helps…


  1. Hey there,

    I’m building an RV-7A with a Garmin G3X cockpit. I have been thinking about mounting my boxes under the subpanel frame similar to how you went about it. Any regrets and suggestions?

    Great work.



    • For some reason I missed a bunch of comments made on the website…sorry for the extraordinarily late reply, Steve!

      To answer your question, yes, I’d still make a tray but I’d pay more attention to (a) the space needed for connector backshells and wiring harness service loops, and (b) putting the “forest of tabs” ground block where it would be accessible without removing the GTR-20 comm radio from the tray.



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