Bede BD-4C Construction: Day 3

Friday morning was set aside for installing the skin on the inboard end of the right wing, which includes the fuel tank. There were a few prep steps remaining because we simply ran out of time on Thursday afternoon. First, I shortened the fuel pickup line and drilled a new fuel strainer in the end.

Not pictured is a little plug which blocks the end of the tube so everything is forced through the strainer.

Then Steve and I moved on to the fuel sender. It has reasonably long lead wires but not long enough to reach the wing root so we extended them. Steve’s preferred method is to crimp a non-insulated butt joint connector, melt a little solder into it, and then finish it off with heat shrink tubing. By staggering the placement of the butt joints, we ended up with a neat set of four wires all wrapped in corrugated loom. This was my first chance to solder with one of those mini butane torches and it worked great. I cannot believe I have lived this long without getting one of these tools.

I got a quick side lesson in deburring the edges 0.063″ aluminum with a file and thought, briefly, that this was truly the glamorous side of aviation. But then… drum roll… it was time to mix ProSeal… a lot of it. To be specific, there are 4.5 lbs of ProSeal holding this one piece of wing skin on and sealing the fuel tank. Given the stink, er, odor, I now know that mixing ProSeal is the glamorous side of aviation.

We worked with nine paper cups, carefully labeled “1” through “9.” We mixed them in order and used them in order, to assure that each batch got applied within the roughly 90 minute window.

As soon as the first batch was ready, I used a popsicle stick to seal the gussets that I had riveted on Wednesday, fastening the rear spar to the wing ribs.

I then ran heavy beads of ProSeal along the edges of the ribs and added a second bead (on top of the first bead) on the ribs 12 and 9, which serve as the outer walls of the fuel tank. The idea is the fill in the holes in the honeycomb and leave plenty of ProSeal to seal the tank so that it does not leak. I was again pleasantly surprised at how neat the process was. Between being careful with the popsicle sticks and using the pneumatic gun for applying the beads, I did not get any of the gunk on me or my clothes or on parts of the plane where it did not belong.

I had scuffed up the wing skin where it would meet the ribs. For good measure, Rob added yet another bead of ProSeal, this to the wing skin directly. Rob and Steve mounted the fin in the bottom of the fuel tank, positioned the fuel pickup line in the fin, riveted and ProSealed the clamp over the pickup line, and tightened and ProSealed the pickup line connectors which are inside the tank. I am quite confident that none of this stuff will ever work loose!

Here is a photo of the wing just before we closed it up. You can click on it (and any of the other pictures, too) to see a larger version.

The left-most bay, between ribs 13 and 12, is open at the wing root. The next three bays, between ribs 12 and 9, are the fuel tank and will hold a little more than 24 gallons. At the top, between ribs 12 and 11, you can see the fuel sender (which will drive the fuel gauge). Below the spar, running from rib 12, through 11, and turning down into the red fiberglass fin, is the fuel pickup line. The object taped to the top of the spar between ribs 10 and 9 is the fuel filler neck/cap. After the ProSeal cures, they will cut a hole through the skin, apply ProSeal to the fuel filler neck, and pull it snug to the inside of the skin. The ProSeal will hold it securely in place.

Rob closed up the skin and Steve and he very carefully aligned the edges of the skin with the edges of ribs 13 and 9. Rob and I fastened on the special wing clamps and got to work on the trailing edge. Rob had clecoed the trailing edges of the skin to the rear spar so there was ProSeal oozing out all over the place. We then pulled the clecoes, inserted pop rivets into the holes, and used acetone and MEK to clean the ProSeal out of the rivet heads. This was messy and I went through several pairs of vinyl gloves but, even here, I did not get any ProSeal on my clothes. MEK made quick work of cleaning the errant ProSeal off of the rivet puller. We were in a hurry, being about two hours from when we started mixing ProSeal, so I don’t have any pictures of this phase. Here is the end result, though.

After lunch, Steve gave me a few pointers about working with aluminum. I will still be relying heavily on the gurus in my EAA chapter 32 but I no longer feel like quite such a newbie. We wrapped up the day, and my visit, with Rob and Steve doing a brain dump on tools that I will need. I typed as fast as I could and now have a long list of tools, including brands to buy and brands to avoid, and a short list of reputable suppliers. Since getting home, I have been busily ordering catalogs from the suppliers and even registered a DBA so I could order a catalog from the one supplier that required a business name. I am pleased to introduce “A to Z Aircraft” to the world, a name officially registered with the Missouri secretary of state.

All in all, this was a fantastic three days. I learned a ton about BD-4C construction. I cannot thank Steve Dedauw and Rob Stone and Jim Bede Jr. enough for all the time they spent with me. I know that I slowed them down and probably drove them all nuts with my inane questions. Their patience never flagged, nor did their good humor. I also had a good conversation with Jim Bede Sr. and he was kind enough to sketch out a modification that I might make to the BD-4C to accommodate a larger baggage door. He and I also agreed that grandkids are most excellent and that children are sometimes inscrutable.

Next to the 11 days that I spent getting my IFR rating in 1987, these three days were one of the best vacations I have ever taken. I am definitely looking forward to spending more of my vacation time working on my BD-4C kit.