Elevators 9-11-1 to 9-11-6

Now it was time to begin riveting parts to the elevator skins. First up were the trim cable access panel doublers. Before riveting these to the bottom skins, I had to attach the nutplates to the doublers. This was easily accomplished with the pneumatic squeezer.

Nutplates riveted to the access panel doublers... inside...

...and outside

I then proceeded to back rivet the doublers to the skins as instructed in the plans where AN426 3-3.5 rivets were called for. I ran into a couple of issues here

1. I noticed the rivets had a tendency to lean over as I was back riveting even as I held the rivet gun as perpendicular and tight to the doubler/rivet as I could. A search of the VAF forums suggested that the lean may be caused by the rivet being too long (and it did protrude more that twice the diameter when inserted) and/or by the hose air pressure being too high. The bent over rivets were noticeably worse on one of doublers, and I ended up drilling out several of them and setting replacements with the pneumatic squeezer. I also touched up the scuffed primer with a q-tip.
2. After riveting the doublers to the skin, the skin along the top of the doubler didn't lay completely flat. I saw this on both doublers. This should not be an issue though because when the forward spar is attached to the skins it will pull it tight.

I am not sure why the plans called out to back rivet these doublers in place because it would have been easier to use the pneumatic squeezer for pretty much all the rivets here (and would have saved me some time having to drill out bad rivets). I'll practice on some scrap to see if I can refine my technique for back riveting longer rivets, but for now there are no more 3-3.5 rivets that need to be back riveted.

Left doubler attached to skin (after replacing some rivets)...

...and right doubler also attached

Next I had to rivet the rib halves to the elevator skins. These were also back riveted in place, and I just had to make sure that the rib halves were correctly placed on the skins in the correct orientation. The plans had a clear diagram making this easy. 

I did also switch to using a 12" back rivet set for the rivets next to the longer sections of the larger rib pieces. This was due to the shorter back rivet set interfering with the web as I placed it over the rivet. All rivets turned out nicely though.

Rivets inserted into dimpled holes and held in place with rivet tape

Rivets poking through on the inside of the skins

Checking that all rivets are the same length (I did find a 3-3.5 rivet standing tall among the 3-3 rivets, and replaced it before riveting)

Rib halves riveted to the skins

Back riveted shop heads look good

Larger rib halves riveted in... here is where I used the 12" back rivet set to set the two rivets on each rib nearest the leading edges of the skins

All rib halves riveted to the skins

The next steps in the plans have me attaching the rear spars to the ribs. Before doing this, I wanted to do one more test fit of the spars and elevator skins to verify that the spar flange angles were correct and that there would be no twist in the elevators once riveted together. I had adjusted the flange angles of the elevator spars earlier, and this additional step would help make me feel more confident to go ahead and start riveting the remaining elevator pieces together.

I was very happy to see that when I clecoed everything together, the spars fit perfectly and the skins were held tightly with no perceptible twist, so no adjustments in the spar flanges are necessary. 

Elevator skins and spars clecoed together one final time

Front spar alignment looks good and the clecoes lay flat on the work bench

Both elevators clecoed... skins are tight and flat

With the skins fitting together well, I disassembled everything and proceeded to rivet the rear spars to the ribs. Starting on the right bottom skin, most of these rivets were easily set with the pneumatic squeezer. 

I did initially try placing the manufactured head on the spar side (facing outward) but found that as I squeezed with the hand squeezer (as the pneumatic squeezer was awkward to hold with the cup set on the moving part) the rib flange pulled away from the spar. I ended up drilling out that rivet and went with the convention of placing the manufactured head of the rivet on the thinner material (rib side), which also actually made it much easier to hold the pneumatic squeezer in place at the start of riveting. 

For riveting the shear clips in with the spar and ribs I switched over to using the Main Squeeze hand squeezer. The pneumatic squeezer was too wide to fit next to the shear clip, but the Main Squeeze has a much narrower profile so was able to fit even though I had to push the shear clip to the side a little while riveting. However, this worked well and the rivets were set nicely with no permanent deformation of the shear clips or the skin tab next to the inner shear clip.

Outer shear clip riveted using the hand squeezer

Inner shear clip also riveted with the hand squeezer, with some minor scuffing on the shear clip where the squeezer pushed it to the side

Shop heads on the inside of the spar looking good

Manufactured heads on the other side of the spar also looking good

I then did the same on the left elevator top skin, and this went much quicker.

Rear spar riveted to left elevator top skin

No issues setting the rivets from ribs to spar

Build Hints

• I would recommend using the pneumatic squeezer to rivet where possible even if instructions call out for back riveting (as was the case for the trim cable access panel doublers)
• Using a longer rivet set requires a 1-2 notch increase in air regulator pressure to provide the same force to set the rivets compared to a shorter rivet set. This is due to more of the rivet gun energy being absorbed before it reaches the rivet
• Test fit pieces a final time, if necessary, to check alignment. I believe this is especially critical for parts that play an important aerodynamic role, such as rudder, elevators, and later the ailerons and flaps

Time Taken:     7.7 hours

Dates:                December 1 - December 6 2022

Elevators Total Time:           57.4 hours

RV-10 Build Total Time:      221.1 hours

Priming Total Time:                     24.8 hours (not included in build time totals)