Fuel Fabrication Frustration
Another one of those days in the shop for a long time with little to show for it. I did become adept at turning 3/8" 3003 aluminum tubing into scrap. I know this is a troublesome area for others too. I started out working on the boost pump to firewall line. This short piece had some small offset bends that were difficult to make precisely. That and getting the length exactly right wasn't easy either. The line flares need to mate with the fittings on either end. Using the flare nuts to draw the fittings tight isn't correct nor is there any play or give in the line for that to happen. It's pretty rigid. So getting the small angles bent just right so everything lines up, the flare nuts thread easily AND have the line the exact proper length took me 4 attempts. From there it was on to the fuel selector inlet lines of which there are 2. These proved troublesome too. I lost track of how many I made but enough to use up my entire 10' supply of spare tubing. More has been ordered and thankfully it's cheap. The struggle here was getting the flare to line up correctly with the wing root fitting that has limited access. Once you make that last 90 degree downward bend you're committed. If its off just a little it won't work. You can't un-bend and re-bend it. It's now scrap. The frustrating part was I was following the plans precisely with measurements and angles. The completed lines matched the templates, and the templates are correct dimensionally. But when bent to spec things just wouldn't line up. So I had to deviate from the plans using my failures as templates. Finally I ended up with one that's acceptable. I took notes and learned a lot in the process so I think I can improve upon it when I get more tubing. I also ordered stubby 11/16" and 13/16" wrenches and a 13/16" crows foot for the hard-to-reach flare nuts and bulkhead nuts.