Electrical Wiring

Next, I'm working on a tray that goes right behind the baggage bulkhead in the upper part of the fuselage, right under the top skin. This will hold the magnetometer, or ADAHRS, for the instrument panel. It's essentially a very sensitive electronic compass, gyro, and attitude sensor. It has some specific requirements to be mounted in such a way so that it's oriented in line with the airplane's main axis, and away from any magnetic sources, motors, magnetic metal, etc. It has been found from experience that this is a good place for it. So after a lot of reading, careful consideration and thought, I measured out some material and built this little tray. The white template is where it will mount, and I even drilled the 4 corner holes. So when I get this part, it should just bolt right onto this tray. I made it this big so that there's room behind it for a second one, and the associated wires, pitot and static tubes, and so on, should I decide to add a second screen sometime in the future. The bracket on the right will bolt on to the bulkhead in the fuselage. I'll show you that in a minute. I even bought some special non-magnetic nuts & bolts to fasten this on with.

Here's the bulkhead inside the fuselage, where it will bolt on. I could rivet it on, but instrumentation changes rapidly in aviation these days, so I'm not riveting anything like this in place. I'll bolt it in, and have the option to remove it or change it at some point, if something else comes along to replace it some day. Below, I drilled out one rivet and drilled the other holes for the bracket to fasten on here. Below and behind, by the way, you can see my static lines on the next bulkhead.

Here's a test fit, with the bracket clecoed on to the bulkhead. Now I need something in front to hold the front end of the tray solidly in place.

Funny, the tray wanted to warp and not be nice and flat. So I riveted some stiffeners underneath it, and the angle on the front end with another stiffener and the vertical arm that will hold it to the fuselage. Maybe a bit of overkill, but now it's nice and flat! Here it is all primed and ready to go.

Here I've clamped it inside the fuselage, and I'm about to drill a hole in the vertical support angle. I want to check to get it as level as I can first.

I'm happy with this. It's ready to go! You can see why I left the top skin off the fuselage as long as possible here, to get these things finished first. Can you imagine crawling in back here and doing this later, with the skin in place?

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