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.