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Joe Graham's Online RV-7 Builder's Log

More Horizontal Stabilizer

03-26-06
After the Spar doublers and outboard hinge brackets were riveted in place, the center hinge bracket assembly was bolted into position.

The nuts used for these bolts are "self-locking". They have a nylon core that makes them very secure - you can see the red nylon material in the picture below. The bolts are AN3-5A which have a 10-32 thread. The specified torque value is 25 inch-pounds. But you also have to account for the resistance force of the self locking nuts themselves. This is about 6 inch pounds. So I torqued every thing to 31 inch-pounds.

Remember the HS-710 and HS-714? Here they are riveted into place. There were a few spots that I scratched when riveting, so after everything was together, I shot a light coat of primer on top.

Here's the back side of the spar joint. Notice that the center rivets on each side of the seam are AN426 flush rivets. The spar from the Vertical stabilizer will eventually be assembled against the surface here so the center rivets have to be flush with the surface.

This is a picture of the HS 404 nose rib flange. These holes are the ones that were drilled through from the other side a few pages back. There are four HS pieces coming together at this joint so they were a bit tricky to drill and the are somewhat difficult to rivet as well.

Case in point. This is the HS405 rib side of the joint. The two rivets holding it in place are very difficult to get to with a squeezer due to all the structure around them. I did get the rivets set, but as you can see below, they have a bit of "tip" to the shop heads. Normally, I would want to replace them, so I called Vans and asked if I should drill these out and re-rivet them. They said that this rib has very little tension force acting on it. So as long as there is a shop head formed that will hold the rib in place, it is more than adequate. They said a lot of builders have difficulty with this assembly and that the damage done by drilling out and enlarging the hole is much worse than a tilted shop head. This makes sense. The rib flange is already cut down to fit between the 710 and 714 angles, so its evident there is not much tension force here. It is mostly shear force. So I took Van's advice and left them. I think in the future, I will set these "problem" rivets with a bucking bar rather than the squeezer.

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All photos by Joe Graham unless otherwise noted