Empennage

Today I continued my work on the rear spar for the H.S.

Now that the edges of the stiffeners have been "radiused", or rounded smooth, the stiffeners sit tight in the corners of the spar. I clecoed them in place and drilled out the holes with a #30 bit to full size. The strategy here is to cleco every other hole and drill the empty holes. Then you move the clecos over one hole and drill out the rest to full size.

Here they are, drilled to the spar. Next, it's time to start work on the center bearing assembly that sits right in the middle. I will also be installing some brackets that hold the elevator bearings to the spar.

This bearing is sandwiched in between these powder-coated steel brackets, and drilled together. Six rivets will hold it all together. This bearing sits in the middle of the HS spar and will eventually work to move the elevators up and down on the tail. Only one of the brackets has the 6 holes already in it. So you clamp the bearing in between the two brackets with a clamp, then cleco the brackets to the spar. Now that it's in place you drill holes through the first bracket through the bearing and the other bracket and cleco as you go. Then you take it off the spar. The bottom two holes can't be reached until you take it off, but by now it's held firmly in place with the other 4 clecos, so you can finish drilling the last two holes. Here's the assembly, all drilled.

Then you remove the clecos and take it apart. The small blue sharpie marks show me the orientation of the bearing so that when I put it back together it goes back in the same place. Next, the holes are all deburred. Then, I primed the steel flange of the bearing so it won't ever rust. I used my SEM spray can of self-etching primer. It's the green color seen above. It comes in green, black, or gray. Not that the color matters. Green is just the one they had in stock when I bought it. I taped and trimmed the tape around the center of the bearing to mask it off, so I wouldn't get paint inside the bearing. Then I sprayed it on both sides. This paint dries fast! It's ready to cleco back together for riveting in no time.

Here it is, clecoed back together, ready for riveting. It's exciting to think I'm about to set my first rivet! I have to set my rivet squeezer to the proper length rivet first, so I practiced on some scrap material, then set it so it won't quite squeeze the rivet enough the first time. I'd rather set it that way and then adjust it to more and more squeezing until I get the proper size bucktail on the rivet.

MY FIRST RIVET!! It's a bummer to have a blurry picture, but this is the first rivet for my airplane. One down, only 15,999 to go!

All finished. This is fun! I especially like this cool tool... my pneumatic rivet squeezer. It's one of the first tools I bought, when Avery Tools had a rare sale on them. The dark blue metal piece at the bottom of the picture is a rivet gauge, used to measure the tail of the rivet to make sure it's within specs. You know you've squeezed the rivet enough when the tail is smashed enough that it almost barely fits in the hole on the left side, or the notch on the right side.

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