February 7, 2010

Elevator Pushrods - 4.5 hrs.

Well, everybody, it's a big day for a lot of people out there in TV land. It's STUPOR BOWL SUNDAY. Woop-de-doo. I've never been much of a fan of professional sports. What a colossal waste of time. So instead of watching the stupor bowl, I went out and did a bunch of shopping today while the lines were short and I did some other things around here, and still managed to get some time in the shop on the project. Okay, end of rant.

I mentioned earlier that in my big priming session the other day, I primed the insides of the elevator pushrods. Well, they've been laying around here drying. Rather than try to find a place back on the shelf or somewhere in my crowded shop to store them, I thought, why not just install them in the plane? I see no harm in doing that now, it'll get them out of the way and allow me to check one more item off the list of tasks. So I got busy to get them finished up.

Measuring for the rivet holes on the ends of the tubes is easy. Wrap a piece of paper around the tube and cut to length just so the ends meet. Then fold the paper in half, then quarters, then eighths. Unfold, and you have all the fold marks for the rivet spacing. You can then mark the paper for the edge distance, and tape it back on the tube. Install the end piece and go to the drill press, drill and cleco all around. So simple. And dead-on accurate. It's just as easy for the smaller forward tube which has six rivets. I didn't take any pictures of all that. I think you get the picture. Then, once they were riveted together, I cleaned them up for priming. I took a break while they dried for a little while, and then installed them in the plane.

First, I measured as close as possible to get the spacing just right between the bearing holes on the ends. The plans are very specific about how long these pushrods are supposed to be. Particularly for the shorter, smaller forward pushrod, this is MUCH easier to do now than after it's installed. Then I discovered that after all the careful measuring and torqueing the stop nuts, this part won't go in the plane. It's just a bit too long! There's just no way to get it in there unless you remove at least one of the rod end bearings. So I left the stop nut exactly in place and removed the rod end bearing. It just barely fit in, then I tighened the rod end bearing back down to the nut. So I should have the proper length set.

Then, starting at the front end, I attached the pushrod to the control column weldment under the seat ribs. I don't know how you could do this task without some washer wrenches. It's not easy working down in here, but doable.

The forward pushrod passes underneath the flap motor housing, through the F-705 bulkhead, and on back through the F-706 bulkhead.

Before going any further, it was time to install the bellcrank parts. They have been sitting in my cabinet since I finished them several months ago.

Once again, washer wrenches were indispensible here to get these things installed. Above, the larger aft pushrod attaches to the top of the bellcrank and goes all the way back to the tail, as seen below.

Looking back through the fuse, you can see the pushrod going all the way to the end of the tail. I put a rag over the F-711 bulkhead opening so it can lay on it and not rub the primer off

And... joila! The end shows up just where it's supposed to, in between the F-711 and F-712 bulkheads. Now I'm even more ready to mount my empennage in the not-too-distant future.

And then... my heart just sank through the floor. I lifted the end of the pushrod up off the rag and moved it forward and back to test the movement. It's very smooth but it's hitting something. It's hitting and rubbing on something midway through it's swing. I inspected every inch of it that I can see, and all my connections, and found nothing wrong. It's not the big aft tube. It's the smaller forward one. I know the tube is as straight as an arrow and not bent or warped. I can't imagine what's wrong. It's somewhere under the flap motor housing. Maybe where it goes through the F-705 bulkhead. I'm going to have to take those covers off (maybe even more) and see if I can find the problem. I looked at the drawing, and the hole in the F-705 is cut right down to the stiffener. I don't dare enlarge the hole, if that's where the problem is, without weaking the rear wing spar stiffener. I quit for the night feeling very discouraged.

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