The only thing I accomplished yesterday and today was fitting and match-drilling the fuel filler cap and drain valve flanges. The only area which requires more-than-usual care is making sure that the curavture machined into the filler cap flange aligns with the upper tank skin curvature. Holding the flange approximately in place against the skin and rotating it slightly will give you a feel for where the fit is best. Once the rotation is correct and the opening is lined up, clamp and drill.

Looks good with the cap in place, huh?

Sorry, no pictures of the drain flange drilling process.

The right fuel tank gets a standard fuel pickup – an L-shaped aluminum tube mounted to the access plate that picks up fuel from the aft inboard corner of the tank. A few years back, Van’s found out that these pickups could, if not installed properly, rotate up – rendering unusable any fuel below the pickup. The solution for this problem is an anti-rotation bracket, a piece of aluminum angle that fits over the pickup fitting and is riveted to the access plate. Look at the picture and the function is obvious.

The only catch to fabricating this bracket is accurately locating the 9/16″ hole that accomodates the fitting. If the hole isn’t quite right – too far out or in – the fitting won’t fit squarely on the access plate. Maybe I’m the only builder to have problems with this…

Back to airplane building stuff. I spent a day or so refamiliarizing myself with the the plans, then started preparing tank end ribs and capacitive fuel quantity sender plates.

Preparing the inboard ribs is a straightforward task with the right tools. I used a flycutter to cut the sender access plate holes, and a unibit to cut smaller holes for the vent lines and capacitive sender BNC connectors. If you use the flycutter, make sure to clamp the rib firmly to the drill press and keep your hands or other appendages clear while the cutter is working. It will make a mess of the rib – or your hands – if you don’t.

After the hole is cut, the instructions call for locating and match-drilling the cover plate screw holes by clamping the cover plate to the rib. That requires some extra work to make sure that the cover plate is actually centered on the hole. It seemed to me that it would be easier to center the stiffener ring on the rib and match-drill the holes that way – so I did. The only catch is that ring must be rotated so that the holes will allow the access cover’s flat forward edge to line up with stiffening ridge pressed into the rib. Clear as mud, right? Here’s a pic of one prepped rib, with the stiffener ring platenut holes drilled and dimpled.

The left tank will be fitted with an inverted ‘flop tube’ fuel pickup. That requires fabricating a couple of ‘anti-hangup’ guides that keep the flop tube from becoming lodged in or around the access plate or between the tank stiffeners and ribs. Here’s the access plate guide, it’s just a strip of 0.025″ aluminum bent, drilled, dimpled and riveted to the stiffener ring. Looks like this –

Here are the left and right tank end ribs with stiffeners and nutplates installed. Nothing unusual here.

I’m fitting my tanks with capacitive senders. The sender kit comes with two aluminum plates for each tank that must be drilled to ribs, then outfitted with nutplates and connectors. The plates are attached to those ribs with plastic spacers and insulators; more on that later. Here are a couple of plates ready to have the connectors covered with Proseal. The square cutouts on the bottom of each plate fit around the fuel tank stiffeners.

…and I’m back from Africa. It was a long trip – we traveled to Dar es Salaam and Zanzibar, Tanzania, then to Nairobi, Kenya, and finally to Kampala and Soroti, Uganda. The work was tiring and stressful, but I’m glad I went. I’m not gonna do a travelogue, but I’ll throw out some some pics for all you aviation types.

First stop – Zanzibar. For those of you in the States who slept through geography in high school, Zanzibar is an island in the Indian Ocean off the cost of Tanzania. It’s a prime tourist destination, and there are lots of GA airplanes flying tourists from Dar to Zanzibar. We hopped a short (~20 minute) flight to the island in a Cessna Caravan – a neat airplane, and very popular in that part of Africa. Here’s our flight on the ramp at the Zanzibar International Airport.

Only someone with my juvenile sense of humor would appreciate the unintended wordplay in the shrubs at the Zanzibar airport.

The next stop was Nairobi. We visited both the main international airport (Jomo Kenyatta) and the largest GA airport (Nairobi Wilson). There are a lot of ex-Soviet aiframes flying around east Africa. Here’s an Antonov An-12 transport parked at JKIA. Some of these airplanes are barely airworthy and are used for running guns and other illegal stuff around the hotter spots in Africa. This one actually looks pretty reputable.

These Mi-8/Mi-17 helos were parked at Wilson. They had been used for UN relief work, but were no longer flying.

Last stop – Entebbe/Kampala, Uganda. This picture is of the old Entebbe terminal and the UN relief aircraft flying personnel and supplies to the Sudan and DR Congo. Those of you who were paying attention to the news in July 1976 will remember that this terminal was the scene of the famous “Raid on Entebbe” by Israeli special forces who freed passengers from a hijacked French airliner.

Some more progress made on the tanks, this time fabricating and match-drilling tank stiffeners.

After that, fabricating the T-405 tank attach brackets was next. This was a lot of work, and the plans aren’t much help. A full-scale layout would have made this job a lot easier. There’s also a bit of guesswork to make sure the brackets fit into the tank leading edge with some room to spare for rivets. But they’re done, and I think they look good.

There will be no updates for awhile, probably until mid-November. I’m off to Africa again, this time for work.

I’m sure everyone who surfs this site (all three of you, including my mom) has been wondering why there are no updates. Our move to the new house took most of the summer, and then we disappeared to South Africa on vacation. It’s September now, and the shop is back up and running, so it’s time to get back to the tanks.

Here’s one tank back in the jig for match-drilling and countersinking of the skin-to-baffle holes. This process is slightly tricky, since the tank skins are exactly the minimum thickness (0.032″) for countersinking.

Captain John stopped by for a visit. We think that the wingtip plexi would make a great low-profile canopy.

After the Z-brackets were in place, I followed the Checkoway MethodTM and fitted the clecoed tank on the wing.

With the tank in place the inboard Z-brackets were drilled, and after the outboard leading edges were removed, the outboard Z-brackets were drilled as well. Read and heed Van’s instructions to use a drill stop when doing this work – it’s damn easy to drill into the spar web or stiffeners if you’re not careful. Here’s a pic of the inboard bracket.

After the Z-brackets at each end of the tanks were drilled, the tank skins came off and the other Z-brackets were match-drilled to the baffles. Here’s the left tank with skin removed, just before match-drilling.

With drilling complete on both tanks, the wings came out of the jig for our move to the new house.

The last two weeks have been hectic. We’re on the verge of closing on a house, so that means getting the wings to a point where everything, including the tank-to-wing attachments, are aligned and match-drilled in the current jig.

I don’t have any pictures of the Z-brackets in fabrication, so you’ll just have to imagine the process of drilling the brackets to the wing, then deburring, alodining, priming and riveting nutplates to them. Here’s a pic of the final product on one wing – the Z-brackets are bolted to one wing and ready to be drilled in assembly with a tank baffle.

I’ve been helping John Sannizzaro with his fuel tanks, so I’m not too worried about the process. In fact, I’m looking forward to something that doesn’t require very much priming. I’m really learning to hate that stuff.

The only question in my mind was whether to follow Vans’ instructions for fitting the tank to the Z-brackets, or to use the modified method that Dan Checkoway details in his website. I decided to go with the modified method; I don’t like the idea of elongating holes in the tank baffles to make them fit, and if some alignment problem crops up in the modified method before drilling any holes, I can always go back to the plans method.

Per Dan’s method, I clecoed the right tank together. All the cautions mentioned about fitting leading edge ribs apply to the tank ribs – even more so, since both the tank skins and ribs are formed from thicker material. That makes the hole alignment process more difficult. As with the leading edge ribs, spending some time smoothing the nose of each tank rib and making sure the flanges are 90 degrees to the rib will help the fitting process.

Here’s the right tank clecoed together.