Elevators 9-13-1 to 9-13-3, 9-12-1 redo

 I clecoed the front spars to the elevator ribs and skins, and prepared to blind rivet the spars to the ribs.

Front spars attached to the elevators

All blind rivets were easily set using the pneumatic rivet puller.

Blind rivets holding the front spar to the ribs (photo taken after completing other riveting below)

While attaching the front spars, I noticed some slight oil canning in the middle panel of the bottom left elevator skin. It looks as though the skin is under some compression from the rivets attaching it to the rear spar around that panel. I did some research and decided that I want to try to fix the oil canning rather than letting it be. This will, however, involve drilling out up to 25 rivets along the bottom left rear spar in the trim tab area.

I will then re-rivet the skin to the rear spar while applying some opposing force to the spar so that the skin remains tight when that force is removed. Thankfully re-riveting can be done using the pneumatic squeezer for these rivets.

Oil canning seen in the 5th panel from the bottom

Clearer view showing the skin compression in the 5th panel

Drilling out these rivets was easy and no holes were damaged. As I drilled out rivets around the compressed panel, I could see the skin compression disappearing, and I only had to drill out 22 of the 25 rivets along that part of the spar before the compression was completely gone and the skin was again tightly held using clecoes.

Skin compression disappearing as rivets are drilled out

With the rivets removed, I will apply a small downward deflection to the rear spar near that panel. This should move the skin slightly to the left (outward) relative to the rear spar, after which I will re-rivet the skin to the spar. The goal will be that once the skin is riveted, and the downward deflection removed, the spar will straighten out and keep the skin as tight as possible thereby eliminating the oil canning.

Using a clamp to apply a slight downward deflection (beyond the level position) in the area of the oil canning, I proceeded to set alternate rivets along the rear spar using the pneumatic squeezer. I took my time and frequently check the skin to ensure that it remained flat and there was no compression. 

Slight downward deflection of the rear spar with the help of a bar clamp

Once I had set 8 rivets along the area of previous oil canning, I released the bar clamp and the rear spar returned to it's original form. The skin has no visible compression in those panels and the oil canning is virtually gone. The skin isn't quite as tight as in other panels, and if you push on it in a specific spot it can deflect slightly, but with the tension more evenly spread across the panels it is a significant improvement over how it was previously.

Skin compression gone and even skin tension across the panels between the ribs

Skin looking flat, so I will set the remaining rivets in the spar

Next I set up and leveled a pair of square aluminum tubes that I would use to ensure that the elevators were completely flat while riveting the front spars to the skins. I raised these slightly off the workbench so that I could use spring clamps to hold the elevators down.

Leveling setup on my 8ft work bench

With the elevator held firmly in place against the aluminum tubes I riveted the skins to the front spars using the pneumatic squeezer and the 4" thin nose yoke (as the 3" yoke would barely fit around the overhanging skin).

Getting ready to squeeze rivets into the front spar

After having squeezed most of the skin to spar rivets, I noticed that several had leaned over slightly causing the shop head to be oval. Some head-scratching ensued, and I determined that the cause was due to me having to unscrew the squeezer plunger very far out in order to get the required spacing to the thin nose yoke. With the plunger so far out, there was some play which would have caused the yoke to squeeze at an angle while riveting.

I ended up drilling out about 44 rivets, and switched to using the 3" yoke to reset them. I had to be careful no to deform the leading edge skins (due to the yoke just fitting over the skins), but the 3" yoke set all the rivets nicely. I also did not rivet the holes at the inboard and outboard ends of the elevators to allow interior access for riveting gussets and tip ribs later.

Skin riveted to front spar, except for inboard and outboard ends

Left elevator front spar rivet shop heads (after replacing some rivets)

Right elevator front spar rivet shop heads

Elevator skins all flat and tight

After having riveted the front spars to the elevators, I rechecked all skins for flatness and tightness and everything looked great. Even the oil canning that I previously fixed by drilling out rivets along the rear spar was completely gone, and I was very happy I took the extra time to resolve that.

Build Hints

• Watch for any oil canning being introduced while riveting, and if possible try to resolve it sooner rather than later. Drilling out a few rivets now is easier than potentially drilling out a lot more rivets later to resolve oil canning issues.
• Be careful to ensure that the elevators are totally flat while riveting skins to spars. Any (even slight) bends may cause oil canning in the skins. A leveling jig really helps here as workbench tops (including mine) may not be totally flat across their length/width.
• When using a 4" thin nose yoke with the pneumatic or hand squeezer, use a longer rivet set (1/2") on the opposite side to avoid unthreading the plunger too far. If the plunger is too far out there will be play in it that will likely cause the rivet shanks to lean over while riveting.

Time Taken:     6.9 hours

Dates:                December 12 - December 24 2022

Elevators Total Time:           70.9 hours

RV-10 Build Total Time:      234.6 hours

Priming Total Time:                     26.4 hours (not included in build time totals)