Dave’s RV-7A Building Log

Did the leak repair on the left tank. I got some plastic syringes from the drug store. They didn’t have a very small tip, but I was able to fit a tip for inflating basketballs onto it. It was difficult to squeeze the ProSeal through it, but it did go through. I used that to squeeze ProSeal into each corner. I then placed a bead of ProSeal along the edge of the baffle along where I drilled out the rivets yesterday. I used a putty knife to shove the ProSeal down into the joint. That worked well. I then riveted it back together and covered everything around the baffle in ProSeal. Fingers are crossed. Again.

Finally got to spend some quality time with the project today. Hooked up a bicycle pump to the fuel pick-up fitting and put a balloon on the vent line fitting. Squirt bottle full of soapy water in hand, I set out to find the leaks. The only place I have leaks is on the baffle. It turns out that only 3 corners of the baffle are leaking. The two top corners are the worst. There the leaks are in the corner and back along the baffle for a few inches. I drilled out the rivets in those locations and will attempt to squeeze ProSeal down in there with maybe a skinny syringe. I’ll also hit the corners with more ProSeal and seal along the outside of the entire baffle. I’m confident I can take care of these leaks without any problem.

You can see the nasty bubbles in the last shot:

Leo was so disgusted, he had to look away.

Bad news. I set up the left fuel tank for leak testing. It is leaking in the corners where the baffle, skin, and end rib meet. I put a big glob of ProSeal there when I was putting on the baffle, but I guess it wasn’t enough. The good news is that it’s easy to get more goop in those locations.

There also seems to be leaks along the baffle edge near the ends. However, these might be a by-product of the corner leaks. I’m going to buy a kiddy pool tomorrow, fill it up with water, and submerge the tank while pressurizing it. That should indicate quickly where the leaks are. I want to fix them all in one session.

Bummer, but not the end of the world.

Here’s the fuel lube and caps I used to do the test. (After the fact I found out that Van’s sells a nice test kit that includes one cap and a nice fitting for attaching a bike pump to the drain flange.)

Since we didn’t get to sealing up the tank yesterday, I thought we weren’t going to get it done this weekend. But Julie was kind enough to help me, even on Mother’s Day. This kindness may have come at a big price. We test drove convertibles afterward. I think she’s hooked.

Sealed up the left tank. I had a lot of miscellaneous stuff to do before dropping in the baffle. There were a few places that I wanted a little more ProSeal, particularly around the end rib. I also had to seal and rivet in the anti-rotation bracket for the fuel pick-up. With that done, I followed the directions exactly for sealant placement for the baffle. The bead of ProSeal needs to be right next to the line of rivet holes for the baffle. I might have put it a tad bit too far forward. We’ll see. [The second image is a little fuzzy, but you can see the bead is some distance from the rivet line. Don’t do this. Put it right next to the rivet holes.]

Julie helped place rivets, and I squeezed them in place and moved clecos around. Then we tackled the brackets with pop rivets. I have to say that pop rivets are easy, but not exactly fun. I had some alignment issues on the brackets and had to chase most of the holes with a #30 drill in order to get the rivets to fit. Not sure what happened there. I dabbed a little sealant on all of the blind rivet heads. From there, I sealed the access panel in place and ran out of sealant. I had just enough to dab on the threads for the socket cap screws. I was going to dab sealant on all of the baffle rivet heads, but I didn’t have any sealant left. I’m not sure it’s really necessary anyway. The baffle should be sealed inside of the rivet line. I think I’ll leak test it and then dab on sealant if necessary.

Even though you don’t think it could take long, this was nearly a 4 hour session with an hour of prep work yesterday.

One trick I discovered is in the use of clecos. The instructions say to cleco every hole. If you do that, you’ll be cleaning literally a hundred clecos. I put clecos in about every 10th hole around the baffle, and then used 6 or so clecos in every hole just ahead of where I was about to rivet. I just moved the same clecos around. That way I only had about two dozen to clean.

I also set the tank forward end up to cure. That should help the sealant creep down into the skin/baffle seam. That stuff really does move around a fair amount while it’s curing.

Whew! What a relief to (hopefully) have that one tank done. I’ll leak test in a few days.

Did all of the cleaning prep-work with MEK for the final session on the left tank. Made sure the inside was cleaned out, cleaned all of the mating surfaces, set out all of the rivets and soaked them in MEK, and prepared all of the tools needed.

More prep for the final ProSeal session on the left tank. Taped off areas that I don’t want sealed. Pulled out all the rivet that I will need. Torqued the vent line fitting to 50 in-lbs using a crow foot wrench. Used a multimeter to make sure the center pin of the coax connector had good continuity with both plates, and no continuity with the tank itself. Likewise, I made sure the outside of the coax was well connected to the tank and not the plates. Made sure one more time that everything will fit correctly.

Did some more prep for the final ProSeal session (on the left tank anyway). I scored the mating surfaces on the baffle. I also decided that the countersinking I did in the skin for the baffle isn’t quite deep enough. There will be ProSeal under the rivets, which will tend to make them stick up. I countersunk the holes just a tad bit more, so that the rivet sits a hair below the surface w/o the ProSeal.

Did some miscellaneous prep work for the final ProSeal session on the left tank. Attached the inboard capacitive sender to the rib. Ground down the nose of an old pop riveter I had laying around. Adjusted the bend on the pre-built fuel pick-up, so that it will lay right on the bottom of the tank. Read through the instructions one more time.

Was gone all weekend, but returned early enough on Sunday to do another ProSeal session. I riveted in the end ribs on the left tank. Along the way I also attached the tip reinforcements inboard and outboard and tank attach angle (with help from Julie), sealed the connector for the other capacitive fuel sender, sealed the coax and vent line connector where they pass through the end rib, dabbed some sealant every few inches along the capactive sender wire to secure it to the vent line, and touched up a few spots from earlier sessions that needed a bit more sealant. Long session. Lots of tools to clean up. Used almost the entire tube this time. The only nice part was that there weren’t many clecos to clean.

Shooting the rivets on the tank attach angle was tricky, but not as bad as I thought it was going to be. We messed up the first two rivets. Drilling them out was a huge mess. Little aluminum shavings embedded in ProSeal. Yuk! But after that we shot the rest of the rivets perfectly. Had to use the double offset rivet set on the rivet closest to the angle. Should have put that hole just a little further forward.

One thing to watch for: When I made the tank attach angle, it fit the inside countour of the rib tip perfectly. After dimpling the rib, it didn’t fit anymore. Plus I had to take off a bit more to make room for the shop heads. Make sure you sand down the angle a bit before putting ProSeal everywhere.

Hopefully just one more session with this tank.

I thought I was ready to ProSeal in the end ribs on the left tank, but I’m not. I figured out that I forgot to put the nut on for the coax connector. I had to cut out that wire and use parts for the other tank, re-crimp, re-solder. And then tighten down the connectors on the inboard sender plate. And then mask off areas that I don’t want ProSeal on (rear baffle, fuel vent and pick-up connector threads). And then I started looking carefully at the rivet heads that I swirled ProSeal on in previous sessions. There are several of those that I want to hit again. And then I had to figure out the rivet sizes to use in various places. But now I am fully ready. Too late to start tonight, though.