Avionics Component Mounting

Over the last few weeks I’ve been splitting time between avionics and engine plumbing while I wait for some hardware to arrive.

There are quite a few remote avionics boxes to mount, and I quickly determined I needed to create a few brackets to make more space. I am mounting most of these remote components to the IP sub panel, which is not all that spacious or strong. I designed a few simple hat sections to provide additional mounting locations, and reinforced the subpanel with C-channels to stiffen it up.

To this sub-panel I am mounting:

  • GTX 45R transponder
  • GMA 245R remote audio panel
  • GEA 24 engine data concentrator
  • GAD 29 data converter
  • GSU 25 ADARHS (x2)
  • TCW IBBS 6AH backup battery
  • Rotax ECU
  • Ground bus bar

All this equipment is a bit more than can fit on the stock sub panel, so I created a pair of hat sections to stack the components. I recycled a piece of defective wing skin to create these hat sections. This wing skin was improperly bent at the factory, but the 0.032” sheet was perfect for this purpose.

Figuring out how much space I have to work with
Measuring how much space between the instrument panel and the sub panel
Defective wing skin finds new life as an avionics rack
Forming the sheet into a hat section in a box brake
Fit check of hat bracket, looks good
Backup battery, GEA 24, and GSU 25s mounted to hat bracket
EIS, AHRS, and Battery mounted
Stiffened sub panel, with rivnuts for attaching the hat brackets
More components mounted for fit checks
Transponder and Audio Panel bracket
Ensuring the transponder can be removed without interference from the adjacent bracket

I’ve also been working on my system wiring diagram. I’m using the G3X manual as my primary reference, but adjusting as needed to account for the additional equipment I have, like the GTN 650xi, IBBS, and second (backup) ADAHRS.

The Garmin G3X install manual recommends using a crimp tool that complies with standard M22520/2-01. Tools made by Daniels Manufacturing Corp (DMC) are the de facto standard for this spec, and honestly there aren’t too many alternatives. DMC tools are the only ones I’ve ever seen used throughout my career in the aerospace industry. Even though the tool is expensive ($371 direct from DMC), I decided it was worth buying given how many connectors I have to build up, and how critical these avionics are when flying under instrument conditions. It’s also the tool that is recommended by Kitplanes magazine.

After waving goodbye to $700, I now own a set of the following tools:

  • Daniels AFM8 crimping tool
  • K13-1 and K42 positioners (for the AFM8)
  • Daniels GMT232 crimper for D436 splices (needed for CAN wires)

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