I pulled off the right wing fuel tank, installed the fuel sender and other fittings, and then leak tested the tank. I wasn’t able to find any leaks using the soap and water technique, so I reinstalled the tank back on the wing.
Today I leak-tested the left wing fuel tank, and with a passing result, I then reinstalled the tank onto the wing.
I seem to have misplaced my two fuel strainer fittings, so I have ordered two new from Vans. Unfortunately they are on back-order, so I have no idea when they will arrive. Without those fittings I had to resort to filling those holes with something with something else. At first I tried duct tape, but then switched to a latex plug that I have from my powder-coating equipment. It slowly leaked, but that was ok since I was using soap and water to test for leaks, and maintaining pressure wasn’t needed. I just gauged the air pressure by watching the bubbles form around the latex plug. It worked out well, and I didn’t find any leaks anywhere on the tank.
With that done, I wasn’t sure how hard it would be to reinstall the tank onto the wing. I rigged up a strap to help give some support, and I was surprised at how easily it went back into position. I was able to get bolts through the spar and into the outermost and innermost z-brackets with relative ease, then I torqued them up and the tank was in position. From there I located and installed the remaining bolts, final torqued them all to 25 inch pounds (plus 10 for thread friction), and applied thread seal. I left off the lower bolts from each position to allow me to install adel clamps once the wiring runs are complete.
Today I installed the fuel sender in the left wing.
The install was fine, definitely easier with the tank removed, and easier the second time around. I sanded away the primer from the rib, around the area where the sealant would go. Then I test fit the sender and made some minor tweaks to the arm position to stop it from hitting the bottom of the tank, and the top skin too. Then I mixed up the sealant and got it done. I should have added some hole location info before I covered the holes with sealant. I had to fiddle around to locate the screws into their holes, and in the process I messed up what should have been the perfect install. Anyway, it looks ok and I think it’s a good tight seal.
Tonight I dropped the left fuel tank, and then found all the parts I needed to install the fuel senders and run the tank test. It took a while to find everything, despite my fairly organized boxes of parts.
I actually started during the day, Jen gave me a hand to lift the right wing out of the way so I could unscrew all the screws on the top of the left wing. Then later in the evening I was able to remove the bolts holding the baffles to the spar and carefully remove the tank.
With the tank out of way, I was able to get a look at some of the countersinking on the spar. Not that great to be honest. Most of the holes have countersinks down to a knife edge, and the edges are not symmetrical. There are signs of chatter during the countersinking process on some of the smaller holes for the access plates, and some of the holes are misshapen.
Next up I located the fuel senders, the floats, the tank drain plugs, the fuel return plug, and screws for the sender.
Then I took a few minutes to test the fuel senders. These should have a range of 30 to 250 ohms when the arm is moved. Both the left and right senders measured correctly, the right was exactly 30 to 250, and the left was 27 to 275, which is close enough.
Now I need to find some product to remove the thin layer of old proseal on the senders, from when I installed them on the last wing. Once they are cleaned up I’ll install them and can start the tank test. I’m planning to do one tank at a time, just to save working space.
Tonight I installed the landing lights into the wings, and then started the process of dropping the tanks to seal and test them.
The landing lights were already built from the last set of wings. Before I installed them I spend some time rerouting some wires to avoid any possible chaffing. Once I run the wires through the wings I’ll install a clamp to hold the wiring. I need to check that these lights are still working, but skipped that step in my hurry to get the job done. I should be able to plug in my power supply and get it working.
Next, I started the process of dropping the tank on the left wing. There are around 80 screws, and 18 bolts, per tank to remove to get the tank off the wing. Access is a problem with the wing in the stand, so I will need to move the right wing somewhere to finish removing all the screws from the left wing.
My plan is to drop the left wing tank, install the fuel sender, then use soap and water to inspect for leaks. If it all looks ok, I’ll then reinstall onto the wing, and then do the right wing.
