These are the mounting brackets for the aft (instrument panel side) of the tank. The 'ears' will be welded to the 1/4-round piece of tubing. The piece as a unit will then be glued and then glassed to the aft corners of the fuel tank. The aft end of the tank will then be suspended by turnbuckles spanning the distance between these tabs and tabs incorporated into the fuselage longerons. [It'll make more sense when you see it in action!]

Here are the new brackets glued in place on the tank. We used Hysol glue with flox mixed in. They also got a layer of glass over everything but the tab itself.

I don't have any pictures of the process, but we spent a considerable amount of time 'reshaping' these pieces to exactly fit the contours of the corner of the tank. The process of welding the tabs in place caused a slight twist in the tubing. It didn't lay flat on the corner so we heated it red hot and re-shaped the tubing. By the time we were done [I had scalded my hand and...] the piece fit perfectly.

My friend had a bunch of carbon fiber angle that worked out well for forward attach points. These pieces were also glued to the tank with Hysol. Hysol is VERY strong stuff. There is NO WAY these things will ever come off the tank.

The original tank installation had the tank being squeezed into place between a lower tray suspended by turnbuckles and the forward deck skin holding the tank in place from the top. I really like our new installation with these brackets at the front of the tank and turnbuckles at the rear.

I wedged the tank into place and drilled through the carbon fiber flanges into the brace that's near the top of the firewall and and spans between the longerons. I then installed a couple of floating nutplates for AN3 bolts.

I guess I didn't take a picture, but once the two AN3 bolts are in place along with the turnbuckles at the aft corners, the tank will not move--not even an eighth of an inch. It's very reassuring!

By eliminating the plywood plate that supported the tank in the original installation, I'm sure I saved at least a couple of pounds, too.

There are a couple of things to see in this picture.

First, we sealed the interior of the tank with a thick, two-part paint. It was pretty thick and gooey, but you can see that it flowed out nicely and left a very nice surface with NO pinholes to cause leaks later.

The square that's taped off surrounds the hole for the filler neck. Near the bottom of the picture is an aluminum bung into which the filler neck will be installed along with a phenolic block we fabricated to glue the bung into.

We taped the surrounding area just to keep things neat.

 

Here's the bung and phenolic block glued into place. We made sure to recess the bung enough to allow the fuel cap filler neck to screw down tightly so that the cap itself would be flush with the fuselage forward skin.