G3X Avionics Wiring

Worked on more wiring the LRU (line replaceable units) or blackboxes for the G3X avionics.

So far, I've just wired up the signal wires (which are the hardest parts). The power wires will come later when I get the actual instrument panel painted and install the switches into places. But these boxes connect to sensors and other boxes that will then display all the information on a screen (Electronic Flight Instrument System - EFIS - if you want to be fancy about it)

Once all this is done, just add the front panel and screen and the panel will  be finished.

Mounted subpanel, wiring work

Installed the subpanel and old instrument panel to see where the G3x black boxes and avionics would fit. As expected, the GTN 650 is longer than the space between the instrument panel and subpanel, so I'll have to cut out a section so it can fit.

I also kept going on the wiring. So far, most of the wiring has been point to point, meaning you simply put a wire on one end and connect it to another. I've been putting off wiring the CAN bus, which allows the avionics to communicate with another. Unfortunately, it's odd how it is depicted in the wiring diagram.

You can see that here I have to make some sort of splice, so that two wires come together and only one wire comes out (actually 3 in 2 out for the CAN lo pin and CAN termination pin). How you physically do this is beyond me. I suppose you can use solder sleeves that make a soldered joint for the wires. I suppose a butt splice would work too, but the idea is to avoid a method that increases the size of the joint too much. The solder sleeves shrink when heat is applied to them, not so much for the butt splice. 

Anyway, here's my first attempt - which I screwed up. 

The method for doing this came from the G3x install manual and this VAF post. Anyway, I'll need some help before I continue on with the CAN wiring. 

Magnetometer bracket, FAB, and subpanel

I made a bracket for the Garmin magnetometer. Apparently you can purchase one for $75 or make it yourself. No surprise, the guy who makes his own plane will make a bracket. Like anything else, I screwed it up the first time.

It came out OK, but was too thin with 0.025 in aluminum sheet. So, I remade it with 0.040 in sheet. Also, this time I used a 2.5 in hole saw to make it appear a little more professional.

What's crazy is the G3X manual specifies that you have to "Align the GMU 22 mounting rack’s forward direction to within  0.5° of the longitudinal axis of the aircraft".

So, I tried to make it as square as possible.  0.5° is a pretty small tolerance, but I think I got it. Here's how it came out:

Next up was the forward airbox. Yes, I had been putting this off. Basically, I shifted to bottom plate about 0.75 inches toward the copilot side so it would clear the mixture arm. I had to trim off the top of the filter because the captive bolts were poking the filter. Design is a series of compromises, I guess. I hate to hack up the filter but I was tired of fucking with it and something had to give.

Finally, I've been working on the subpanel now that I've started wiring the cockpit. The center section was the first up, and it came out well. I'm planning to install the cockpit instruments on the bench rather than in the actual plane (I'm not good at yoga).

The spotty green paint is zinc chromate primer. It's supposed to be a light coat, so while it looks stupid this is what you get. The factor claims you don't need any paint at all because the aluminum has an alclad layer that protects it from corrosion. Oh well, better safe that sorry.