At some point, these hard (as in metal) lines will be done. First, I installed the AN fitting for the 5/16" fuel return line through the firewall. This required making two large washers out of 1/8" aluminum angle scrap I had lying around. I used a 1 1/2" hole saw in the drill press to cut the washers. I then smoothed out the edges of the washers by using a 1/4" bolt and nut through the washer and chucked them in my cordless drill. I then ran the drill (and washer) against the ScotchBrite wheel to smooth the outer edges. Next, I drilled the inside hole to 1/2" to match the size of the AN fitting. Worked out well. Running the 5/16th line was trivial, but a bit tedious to get things lined up right. The hardest work today involved running the 3/8" fuel feed lines from the fuel switch to each tank location. The tough part of this was making the tight 90 degree bend in the line at the fuel switch. Found the proper measurement to be 2 3/16" from the flare to the beginning of the 90 degree bend. The ferrel needs to be up next to the flare BEFORE the bend is made. If you work the bending tool carefully, you will not damage the ferrel or the flare when finishing the bend to 90 degrees. I then fed the tube from the inside out. I also use grommet edging (from Aircraft Spruce part number: M22529/2-2R) where the tubing passes through 1" diameter holes in the main gear mounts (cut a length at just shy of 3 inches to cover the majority of the hole).
Inside view of the 5/16 fuel return line through the firewall
Fuel switch view of the 5/16th line (center) and each 3/8" fuel feed lines (top left and right)
