Deburred the outside of the right fuel tank skin. Deburred and dimpled the tank stiffeners and half of the tank ribs. Drilled the capacitive senders, tank attach bracket, and nose doublers to the appropriate ribs. I’m haulin’. The sooner I get through this tank, the better.
Countersunk the right fuel tank skin to baffle holes. Disassembled the tank. Drilled the fuel tank stiffeners to the skin. Deburred the inside of the tank skin.
I realized that I haven’t been taking many pictures lately. Not much new to see the second time around.
I’m still quite happy that I fabricated all of the parts in pairs. The stiffeners are all ready to go. The tank attach bracket is all cut out. The tip doublers are all deburred. Saves a lot of time on the second wing.
Reinstalled the right fuel tank on the spar. Drilled the tank to the splice plate and drilled all of the tank to final size.
Put the right leading edge back on the spar and re-assembled the fuel tank.
Installed the nutplates on the Z brackets for the right fuel tank and installed the brackets onto the spar. Installed the fuel tank on the spar and drilled the baffle to the Z brackets following the method outlined on Dan C’s site.
Primed right fuel tank Z brackets. The whole session was 2 hours, but most of the time was spent on the aileron stiffeners.
Started working on the right fuel tank. I clecoed the fuel tank ribs into the skin (with some help from Julie) and drilled and countersunk the Z-brackets for the plate nut attach rivets.
Finally worked up the nerve to test the left fuel tank again. I hooked up the manometer with fairly high hopes. It lost 1/2″ after an hour. Not good, but maybe the temp just went down. It lost another 1/2″ after that and then another. Not good.
I pulled the tank outside, put a ballon on one of the fittings and pumped it up. I sprayed soapy water all over the tank and couldn’t find anything. On the third time around the tank, I finally noticed a few small bubbles on one of the fuel filler flange rivets. (You can just see it in the second picture below.) It’s the one that is holding the fuel vent clip. I had trouble with that rivet when I installed it. I didn’t tip the tank on the back rivet plate to account for the bend in the flange and the head ended up proud of the surface. I had to drill it out and redo it. Well, I must not have had enough ProSeal in that one the second time around.
Rather than mix up a whole batch of ProSeal for one rivet, I’m going to fix it when I work on the next tank. Hopefully I can just reach through the fuel filler hole and dab some ProSeal on the inside of the rivet.
Anyway, I’m moving on. I’m quite certain that the baffle is no longer a problem. Woo hoo!
I put the fuel tank on the wing. Things were not lining up well. I had gunked up the ProSeal on the baffle flange a bit thick. I cut that down a bit. Still not fitting. Then I remembered someone on the list saying they had a similar problem that they solved by jacking up the middle of the wing a bit more. So I pumped the jack once–better. Twice–perfect fit. Eventhough I used a line across the spar to make sure it was lined up, I guess there was still a millimeter or two of sag.
A side note on fuel tank testing. I left the ballon on the tank just for fun. After several hours, there was no noticeable decrease in size, eventhough I know I have a small leak. I’d suggest using the manometer method instead of relying solely on a balloon for testing the tanks.
Drilled out the rivets on the left tank in the corner that was leaking. I drilled out about 8 rivets. I scraped and sanded the ProSeal off of that area as well. That stuff really sticks. MEK helped get off the last little bits. I guess it hadn’t completely set up yet.
I mixed up another tube of ProSeal and used a putty knife to jam it down into the seam between the skin and baffle flange. Re-riveted and cleaned up. [Note: don’t put the ProSeal on this heavy over the shop heads. It makes it difficult to put the tank on the main spar. Also, it would have been easier to fix this by just reaching inside the access panel. Oh well, 20-20 hindsight.]
The left tank still has leaks. The one corner that I thought wasn’t leaking actually is leaking at two of the rivet heads. Since they are pretty slow leaks, I was able to get some descent pressure in the tank this time. I soaped up the entire tank and those two rivets are the only places making bubbles. You can see the bubbles around the upper rightmost rivet. The rivet 4 to the left was also bubbling, but not in this picture for some reason.
I haven’t had much time to work on the plane lately. I’ve been trying to fly everyday to get the private pilots license finished up. Having this kind of backward progress is definitely frustrating at a time when I’m not making any forward progress anyway. I guess there is one small bright side. My daughter pointed out that the tank will be very clean from spraying soap all over it (and rinsing afterward).
To anybody making their tanks, don’t follow Van’s instructions where it says to put on a small bead of ProSeal. Make sure you have a healthy bead of ProSeal along the tank/baffle seam. I’m planning on buttering up the baffle flange good and plenty on the other tank.