Kochman Family RV-10 Rotating Header Image

Horizontal Stabilizer

Attached the tail feathers!

Sorry for the lack of updates.  We’ve done some miscellaneous work over the past couple months, which I’ll talk about in a later post.  Over the long 4th of July weekend, we decided to attach the empennage and get everything rigged and tested.  The process was a little nerve-racking since we have to align and match drill large assemblies together.  Any misalignment or wobbly drill could necessitate tedious, time-consuming repairs, and I decided a long time ago that I’m done working on tail surfaces.  It’s also a pain to work with all this stuff attached–it’s really difficult to move around the garage.

First we fit the elevators to the horizontal stabilizer.  This involves installing rod end bearings in the elevators, then bolting them to the horizontal stabilizer to see how it fits.  Fortunately, everything fit great.  Then we fixed both elevators in the neutral position, then drilled the holes that connect the elevator pushrods to the elevators themselves.  That went well, too, with both elevators connected together, they were aligned perfectly, both neutral at the same time.  If you mess this up, you’ll be in a position where one elevator looks like it’s slightly up while the other looks like it’s slightly down, which ain’t good.

Next we took the elevators off and attached the horizontal stabilizer to the tailcone.  I’ve been dreading this for a while, since it requires drilling long, straight 3/16 holes in just the right position.  I used a 12″ long bit, which gave me the necessary clearance but also helped align the hole.  This also went well, so by now I was proud of my hole-drilling abilities.

Next we reattached the elevators and connected them to the control system.  This was really cool–with everything connected, we could move the control sticks up and down and see the elevators move.

We then attached the vertical stabilizer and rudder, and connected the rudder cables to the pedals.  Again, it was fun to push the rudder pedals and see the rudder move.

We also test fit the empennage fairing, and it turns out it fits much better than I’d anticipated, based on the negative feedback I’ve seen in the Van’s forums.

Lastly we removed the elevators and rudder, but we’ve kept the rest of it together for now so we can final fit the empennage fairing.  We figure this will be the last time those parts will be attached until we get to the airport, so better to do it now than then.  With the vertical and horizontal stabilizers attached, we can close the garage door with a few inches to spare.

Here’s Kelly attaching the elevator pushrod to the elevators.

A view with everything attached…

Kelly is pleased by the initial fit of the empennage fairing.

Asssembling the horizontal stabilizer – Part 9

We got a lot of work done this weekend. Kelly spent most of her time removing clecos and taping rivets in place, and I followed shooting the rivets. It’s amazing how quickly the work goes when there’s two working on it. More fun, too. Kelly also learned her way around the pneumatic squeezer. The 252 rivets on the rear spar alone gave us both some practice.

There are a few more rivets right in the middle of the HS; those will be easier to get when we remove it from the cradle. During some downtime, we arleady started working on the elevator ribs.

Asssembling the horizontal stabilizer – Part 8

Finally finished riveting the forward spar to the skins. I also showed Kelly how to rivet; she seems like a natural.

Asssembling the horizontal stabilizer – Part 7

We flipped the HS around so we could rivet the top. In less than 2 hours, I got the top left skin completely riveted to the forward spar. This definitely goes faster with practice.

Asssembling the horizontal stabilizer – Part 6

Unfortunately, I haven’t had much time to work recently. I did get a couple hours in today, and now both sides of the bottom skin are completely riveted to the forward spar.

Asssembling the horizontal stabilizer – Part 5

Finished riveting the nose ribs to the forward spar, except for the inboard nose rib on each side–too difficult to access in the cradle. I’ll do those after everything else on the HS is complete, as the plans suggest.

Next, I started riveting the skins to the forward spar. Where to start? I basically started on the right bottom, from inboard to outboard, skipping every other rivet (where the hole has a cleco). Here’s a picture:

I only got through a few dozen rivets tonight, but I’m ready to pick it up tomorrow.

Asssembling the horizontal stabilizer – Part 4

Kelly left town today, so I spent most of the day working. First up: rivet the HS nose ribs to the skins–a huge pain. A little searching online revealed that this is widely regarded as one of the more difficult places to rivet. After a few drilled-out rivets, I got the hang of it. With the forwardmost rivets, I ended up substituting MK-319-BS blind rivets, which apparently isn’t uncommon. I even heard of one instance where someone used *all* blind rivets for the nose rib to skin attachment.

Here’s what the skins and forward spar assembly looked like before attaching the two (the next step):

After the unpleasantness of the nose ribs was over, I dropped the forward spar assembly into the skins and clecoed it in–really starting to look like the complete part! I started riveting the forward spar to the nose ribs before ending the day.

Asssembling the horizontal stabilizer – Part 3

All we did tonight is put the HS skins in the cradle and cleco the nose ribs in place. We found it worked best to cleco the nose ribs to one side of the skin, put the skin in the cradle, then cleco the other side. Chuck (the previous owner) did an excellent job preparing the nose ribs–no hint of the flat spots on the outside of the skin that are often caused by the rib flanges.

Asssembling the horizontal stabilizer – Part 2

Tonight we finished riveting the inspar ribs to the front spar (aside from the innermost and outermost). Next up: riveting the nose ribs to the skins.

Asssembling the horizontal stabilizer – Part 1

With all the HS pieces deburred, dimpled, and primed, we’re finally getting to the HS assembly steps. Since we purchased this kit partially-complete, this also happened to be my first time riveting since the class I took back in April. In retrospect, I should’ve practiced squeezing on some scrap first or at least started with an easier task. Unfortunately, the stringer web took the brunt of my rustiness in the form of a few scratches and minor dents (since I also tried bucking a couple of the AN470AD4-5 rivets to the stringers). Nothing major, but I’ll need to buff out the scratches and re-prime the piece. You can see the dings here.

The biggest problem is that I had the pneumatic squeezer set up incorrectly—the gap was too small, so the squeezer was reaching the rivet earlier in the stroke, where it didn’t have enough power to squeeze it. Let’s just say now I know the squeezer develops most of its force at the last 1/16″ of the stroke, and it took me a while to figure that out.

The rest of the day went better. The picture below shows progress at the end of the day—about half the riveting of the inspar ribs to the forward spar is complete. We probably got 50% of today’s real work done in the last 10% of time.