During the process of inspecting each rivet for blue fuel dye stains, my heart sank when I found a rivet hole without a rivet.
In the photo above, I have an alignment punch stabbed through the proseal filled hole. After much thought, and consultation from VAF, I decided to countersink the hole to accept a countersunk closed end blind rivet. The pictures below show before and after countersinking. For good measure, I was able to contort a piece of AL to slather a blob of sealant on the shop head of the rivet. The good news is that even if it didn't seal completely, the location of the rivet makes it highly unlikely to leak.
I leak tested my first tank about a week after completion (November) using the schrader valve and balloon method. After a few attempts at getting the balloon to seal on the vent line, I sprayed soapy water liberally over every rivet. Success!! Leak Free!! Fuel Tank Complete!! Not so fast.....
My second tank was completed not long after the first but for whatever reason had not been leak tested. I got busy with wings and basically kept putting it off. One day I came across a thread on VAF regarding the difference in flaring tools, automotive vs aircraft. I decided to read a little deeper since I bought my flaring tool (used to fab the vent lines) from autozone. I then went down a whole different rabbit hole on what happens if the mismatched tubing flare and AN fitting are mated since one is 45 degrees and the other is 37 degrees. A potential leak path between the internal tank bulk head fitting and fuel vent line could be a problem, causing a constantly dripping fuel vent to venting and fuel feed issues. I decided I needed to halt all work on the wings and circle back to my tanks and see if I had a leak. I used about 6-7 gallons of 100LL to test the tank. I placed the tank in its cradle and laid it down, filled with gas, for a few days. There was no evidence of leaking any where.
I didn't get any photos of what I'm about to describe but next, I propped up the outboard end of the tank so that the entire inboard baffle including the vent fitting would be covered in fuel. Once again no leaks leaks were found, but that doesn't mean that I'm free and clear. Once the plane is flying, vibrations or what not could case the fitting to begin leaking at which point I'll have to decide what to do. The proper fix is to replace the vent line with a properly flared fitting. However, the only access to the inside of the tank without cutting a hole is through the fuel float hole.
While installing the fuel pick up assembly/finger strainer, I couldn't figure out why I had so many threads left outside the hole after tightening the assembly. I posted the question on VAF here and felt like an idiot afterwards. I'll just chalk this one up to a brain fart.
The picture below is what the inboard side of the fuel pickup assembly.
What better to do on a hot muggy, rainy, November day? Why work on an airplane of course. Louie was not impressed with the rain and kept a safe distance from the wet stuff.
All I really managed to accomplish today was build up some frustration while I worked on the fuel floats. However, there were two valuable lessons learned:
1) As the pictures shows, there are two different fuel float part numbers (L & R). I apparently glossed over the plans and failed to notice two different part numbers on the box. I finally realized something was wrong when I just couldn't get the holes on the sending unit and the inboard baffle to line up.
2) If after bending the float wire the float just isn't quite right and touches either top or bottom of the skin, cutting it shorter does not work. These wires are pretty stiff, and once they are bent at a 90 degree angle it is difficult to unbend or straighten them. So Van's got another $5 from me and sent me a new wire. In the meantime I used the wire for the other sending unit (which I managed to not screw up).
As with most builders, I didn't get too many pictures of proseal in action. Before I got to the fun stuff there were are couple of tooling holes in the end ribs that needed to be filled with #6 rivets. The plans suggested mounting the rivet gun in the C-Frame to buck these. I used that method for the first few, but I overlooked the other end ribs and installed them without first filling the holes. I bucked these using my 5lb back rivet bar with no problems.
After seemingly endless prep work on the skins and stiffeners I finally had my first proseal session. It was messy and nasty, but I knew that going in. Many people apply the proseal and 100% cleco and wait for the proseal to cure before riveting. Again, I decided to stick with Van's and rivet them wet. It was not not fun, but mission accomplished.
I wasn't quite sure how I was going to be able to countersink the fuel filler flange but a scrap piece of wood and a clamp was all it took to hold things steady as I worked my way around the flange with the CS cage.
I used the same technique I used for dimpling the rudder. Attach a piece of safety wire to a bungee that is attached to the garage door track. This allowed me to easily dimple the skin by holding the folded over skin open and out of the way.
I have a love/hate relationship with preassembly of parts. On one hand, its satisfying to see a big part come together out of a pile of other parts, but on the other hand you know its all just temporary and it has to be taken apart again for other prep work before final assembly. The wings are unique in that you get to experience this love/hate thing not only once, but twice (once for each side).
I got everything put together and set in the cradle and went to town countersinking the tank skin where it meets the rear baffle. As with many other parts of the build, there is a much contention as to which method is the best. I'm sticking to the plans and countersinking instead of dimpling.
After getting all of the stiffeners ready to go, I pulled the tank skins out and started clecoing things together to see how it all fit. For the life of me I couldn't figure out what the "extra" strip was on the end of the skins. I searched the plans backwards and forwards and finally resolved to posting a question on VAF for help. Wellllllll.......As it turns out, these strips were removed in a previous section. I guess that's what I get for skipping straight to Section 18.