December 15, 2019

Center Console Work

I’ve been pretty quiet with blog updates for the last 2 weeks as I’ve been doing a lot of research and planning for upcoming tasks: running wires, fuel lines, and brake lines. I wasn’t planning to have this all figured out by this point in the build, so this hit me a little bit by surprise, but I’m going off recommendations from others to do these tasks now before attaching side skins while it’s easy to access. I’ll cover wiring in a separate post related to the avionics.

For fuel lines, I’m running solid aluminum tubing based on recommendations from STOL Creek Aviation (the US dealer for Edge Performance). Reasons for doing this: they will last the lifetime of the airframe, they are lighter than rubber hose, and I don’t need to worry about it corroding due to fuel additives. I ordered 50 ft of 3003-O Versatube from Aircraft Spruce in 3/8” diameter. I’m using the same size for both supply and return lines. Originally I was going to use 5/16” size for the returns, but that would mean AN5 size fittings, which are a somewhat uncommon size. Yes, you can get them from Spruce, but there were going to be a few places where I’d have to get AN6-to-AN5 reducers (such as the fuel selector valve), and those reducers are both rare and expensive. I see that on the Sling TSi they went to 8mm tubing for both supply and return lines anyway, so I decided to do the same since I’ll likely have a fuel-injected engine.

Speaking of fuel selector, I decided to go order one from Andair directly. They now offer right-angle AN6 fittings as an option on the FS2020-D2 duplex selector, which is the selector the TAF Firewall-Forward (FF) kit includes. Given the tight fit inside the center console, it seemed like a better option to buy a version with these right angle fittings; the current TAF FF kit includes this same fuel selector, but with female 1/4” NPT fittings, to which you must attach brass 90° elbows, then NPT-to-hose barb fittings. I dislike NPT fittings, so I’m trying to avoid them when possible; and with the extra adapters, every joint is a possible leak point. Since I was able to customize my order from Andair, I also ordered two options: a six-inch lever extension and a universal joint. My plan is to mount the actual selector valve a little lower in the console to make running the fuel lines cleaner/more direct, but use the selector in its original location on the dash. It will take about 4 weeks for the selector to arrive. The pricing was good (better than the price on Aircraft Spruce) since the USD-to-GBP exchange is very favorable right now. While I was at it, I also ordered their GS375 gascolator with AN6 male fittings.

Like the fuel lines, I’m also going to run solid brake lines using 3/16” 3003-O versatube, so I also procured new fittings for the brake components; NPT-to-AN3 fittings for the brake master cylinder and parking brake valve (to replace the push-on fittings included with the kit), and then a bunch of AN3 fittings to distribute the brake lines to the left/right sides and firewall brake fluid reservoir. In the factory photos provided by Craig on his site, I saw a few pictures with the throttle quadrant attached while the interior is mostly opened up, similar to how mine looks now. Since I’m running hard lines for the fuel and brakes, I think it will be easier to complete that routing now. To that end, I assembled the throttle and brake lever assemblies, and started preparing the plate they attach to.

Assembling the brake master cylinder and lever
Mostly complete

Part of the throttle quadrant task includes attaching it to the center console panel. I decided I want laser-etched markings rather than decals, so I spent some of my weekend working out how to do that. I have a small laser that’s mountable to the same 3-axis CNC machine I’ve used before for milling/cutting. I worked out how to prepare the panel (specifically, which combination of paints to use and how many layers), the software toolchain, and the the laser etching settings to use (speed, power, # of passes). I was able to achieve a remarkably good result! Based on this successful test, I painted the center console cover. Meantime, I need to find out what the FARs say for required markings and language, and then create the artwork files.

Test panel painted then laser etched with a sample marking for the throttle (power) lever
Painting the center console cover white for the base layer, then dark gray for the top layer

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