Thursday May 1, 2025
Mounting Electronics, Wiring (Electrical)
8.0 Hours

I got back to work on the panel and subpanel electronics today. First, I trimmed the angle on the bottom of the radio cut-out in the subpanel so the connectors on the audio panel have more space.

I mounted GEA-24 (engine sensor unit) behind the subpanel with #10 nutplates and some AN3 bolts. I want it to be relatively easy to pull off since I won't have access to this area except from below once the top skin is riveted.

Nutplates... I installed a lot of them today.

I also installed GAD-29 (ARINC 429 interface) on the other site of the support rib. Other than power and the CAN bus, it only talks to the GTN 650, so this puts it right next to the back of that.

I installed the two 20 place fuse blocks (one each for main and avionics busses), the avionics bus relay, and the avionics bus 30A fuse. All of these attach with nutplates. I need to order some longer #10 screws for mounting the fuse blocks.

Then I mounted the backup battery on the left lower subpanel.

The battery is decently heavy and the subpanel isn't super thick, so I added some doublers at both ends to help spread the load.

Then I mounted the GSU 25 (ADAHRS) and GAD 27 (misc electronic utilities) above the battery. This spot on the subpanel is solidly tied to the airframe in multiple directions, so hopefully the ADAHRS will be happy here.

I dunno why I took pics of all of the nutplates.

I mounted the CO detector beside the backup battery and GAD 27.

I installed the three pull cables (oil cooler, alternate air, and cabin heat) in the panel so I can start routing them. I drilled holes in the sub-panel for the first two. Still need to create the firewall pass-through.

Then I installed all of the switches on the panel. I wired the master switch to the battery contactor.

Then I started wiring the fuse blocks. I have 6 AWG coming from the battery contactor on the firewall to the main bus fuse block. I also have 6 AWG to the avionics bus 30A fuse and then 10 AWG to a relay and onward to the avionics bus fuse block. I wired the relay to the avionics bus switch and tested both the master switch and the relay with a 12V power supply. All working...

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