Brief Description: Cabin fuel line fabrication - 02
The plans have you fabricate the lines with 3/8th tubing aluminum tubing. The routing for those lines is through the two brackets mounted on the center section, thorugh a grommet near the end of the center section and finall through the skin to the wing. Tom's lines are 7/16ths and come with the B nut already installed. That meant the holes in the brackets needed to be enlarged to 13/16ths to allow the nuts to pass through.
The plans have you use the bottom hole of the brackets (see all three images.) On this bracket there was enough material to drill another hole, but not enough material on the second bracket. There also was not enough edge distance left to increase the holes to the 13/16 need for the B nuts to fit through. To fix that I routed the lines through the holes at the top of the support brackets. Those were already 5/8ths and I had the edge clearance to open them. These are for electrical runs. But I still have the bottom two pass throughs available. One of those holes is used for the brake lines on the A models. I am building a TW so no issue there. I slowly opened the pass through to 13/16ths and the nuts slide through.
The next problem arrived in the turn radius thorugh the support bracket and over to the fuel valve selector. You can see in image 2 the turn is so tight it is pushing the snap bushing out of the hole. Not good. I removed the bushing and wrapped the line in tubing to provide anti-chaff protection, but the radius was still too tight.