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Almost a catastrophic aileron day . . .

catmandu

catmandu

Well Known Member
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Got to page 34-10 today, and needed to countersink the counterbalance tube. Heeding advice about there being definite left and right orientations to the tubes, I started with the left aileron, secured the counterbalance tube in test position one, and went about attaching the aileron skins with clecos to check alignment of the tube holes relative to the nose skin. Trailing edge went on fine, but when I got to the nose skin the skin holes were not close to matching the spar holes and the middle nose rib was off as well. Did I pick up the wrong skin? No, the part number on the label matches the KAI, definitely the left nose skin.

IMG_6603.jpeg

My heart sank with the dawning realization that we must have built the aileron with the spar upside down. How could we make such a dumb mistake! All those rivets to drill out, boy this sucks. Well, let's check the right aileron, see if that is wrong too. Nope, all good, nose skin fits like a glove. So I went back to the KAI, and checked things again and again. Dangnabbit, the left aileron was built right, exactly as shown, and the right aileron is in fact a mirror image.

I finally realized that we had been shipped two right aileron nose skins, one of which was labelled incorrectly as being a left aileron piece. Can't catch that error during inventory! Trust but verify, folks.

BTW, test position one on the right tube was of course wrong, but everything matched when I flipped it and I did get to countersink the proper holes.
 
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catmandu said:
Got to page 34-10 today, and needed to countersink the counterbalance tube. Heeding advice about there being definite left and right orientations to the tubes, I started with the left aileron, secured the counterbalance tube in test position one, and went about attaching the aileron skins with clecos to check alignment of the tube holes relative to the nose skin. Trailing edge went on fine, but when I got to the nose skin the skin holes were not close to matching the spar holes and the middle nose rib was off as well. Did I pick up the wrong skin? No, the part number on the label matches the KAI, definitely the left nose skin.

View attachment 113325

My heart sank with the dawning realization that I must have built the aileron with the spar upside down. How could I make such a dumb mistake! All those rivets to drill out, boy this sucks. Well, let's check the right aileron, see if that is wrong too. Nope, all good, nose skin fits like a glove. So I went back to the KAI, and checked things again and again. Dangnabbit, the left aileron was built right, exactly as shown, and the right aileron is in fact a mirror image.

I finally realized that I had been shipped two right aileron nose skins, one of which was labelled incorrectly as being a left aileron piece. Can't catch that error during inventory! Trust but verify, folks.

BTW, test position one on the right tube was of course wrong, but everything matched when I flipped it and I did get to countersink the proper holes.
Click to expand...
Not sure about the "left and right counterbalance tubes". I measured mine and the holes were within 1/64" on either end. I then clecoed the skins to those holes to make sure they lined up. I then removed the clecos, reversed the counterbalance tube, and clecoed the skin back on. The skin fit either way.

Just a data point...
 
rocketman1988 said:
Not sure about the "left and right counterbalance tubes". I measured mine and the holes were within 1/64" on either end. I then clecoed the skins to those holes to make sure they lined up. I then removed the clecos, reversed the counterbalance tube, and clecoed the skin back on. The skin fit either way.

Just a data point...
Click to expand...
All I know is that when I installed a tube on the right aileron nose ribs, and then clecoed the right nose skin onto the aileron, the holes in the leading edge of the aileron nose skin did not match the holes in the tube on the first try, but did match when I flipped the tube end for end and reinstalled on the nose ribs. I did this as it was previously mentioned here as something to check. But I'm a building noob so maybe I am wrong.
 
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It’s just a bump in the road. Roll with it ( pun intended) and fix it and move on. The ability to recognize and make right is an asset that will benefit you as you progress.

As pop used to tell me, things like this are not a problem. They are annoying interruptions on the way to completion.
 
Pop used to tell me there's nothing you can screw up that can't be repaired or replaced. It's weird how just saying that out loud reduces stress during building.
 
My counterbalance tubes were misdrilled from the factory; the holes either line up with the leading edge or with the screw attach points in the leading edge ribs, but not both. I have been in contact with support, they recommended either re-drilling or waiting for new parts (backordered).

A couple weeks ago when I identified and tried to troubleshoot the issue I compared the tubes by flipping them end to end; as I recall the holes still did not align but I plan to recheck this based on the other post.
 
Looking at my tubes, the mounting holes in the ends of the tube that are screwed to the two end ribs are clocked in the up and aft position. This locates the six holes forward. If you swap the tube end to end and align the end holes, the six holes will not be clocked forward.

Point is, if you put the screws in the end holes through the end ribs, you will end up with 12 holes along the front of the tube. The holes you countersink and use will be dependent on which aileron you are building.

If you have to drill holes in the tube, you are not putting it together as intended…unless, of course, the holes were miss drilled at the factory.
 
I found the exact same issue yesterday with my lower flap skins. Two skins, one marked -001 and the other -002, but they’re both right side skins. And here I thought I’d found something I could actually complete without all the back ordered parts. No response yet from Van’s. This is getting frustrating.
 
I agree with Bob. While I don't have the parts yet the plans only indicate one part number for both tubes. This means they put six holes on either end facing forward for both ailerons but you only use the outboard holes on each. So you have to orient the tubes into the frames so the holes are pointed forward and down, with the mount holes up and aft, then pick the outboard end of each for countersinking.

My second concern is the galvanic relationship between stainless steel and lead is such that these two should not be together without some barrier. I will likely throughly paint the weights since these tubes are readily exposed to rain intrusion.
 
I was considering the use of VHB tape between the lead weight and counter balance bracket to keep the lead and SS separated. Paint would probably work and I also have some left over 1/64” silicone sheet that might work.
 
There is something asymmetric about those counterbalance tubes.
I was reluctant to undertake re-drilling them as support wanted me to do, so I got out all the parts and laid everything out.

Previously, I had picked a tube, prepped and primed and countersunk it. Once assembled, it did not fit in the L aileron (holes were off by about a diameter). I swapped that one to the R aileron, and it fit. I took the other tube, temporarily mounted it to the left, and still no dice … swapped ends, and now the holes line up.

I guess the message is that if things aren’t lining up, try swapping the tubes around. And, fit everything up before you countersink just to make sure you have everything arranged correctly.

Just looking at them it does not make sense (and there is only one part number / no mention of this in the KAI), but after doing the above I have tubes that fit.
 
rocketman1988 said:
I was considering the use of VHB tape between the lead weight and counter balance bracket to keep the lead and SS separated. Paint would probably work and I also have some left over 1/64” silicone sheet that might work.
Click to expand...
It occurred to me that I can also powder coat small parts so I will probably do that to the lead weights.
 
IMG_0128.jpeg

I measured things today. The photo shows the correct installation of the counterweight tube. If you mount the tube with hole B on top, the nose skin holes will not align.

Extend the centerline of the holes available to countersink to the end of the tube. The linear distance along the outer circumference of the tube from that centerline to hole A is just less than 1 1/2”. Countersink the outboard six holes.
 
catmandu said:
View attachment 113359

I measured things today. The photo shows the correct installation of the counterweight tube. If you mount the tube with hole B on top, the nose skin holes will not align.

Extend the centerline of the holes available to countersink to the end of the tube. The linear distance along the outer circumference of the tube from that centerline to hole A is just less than 1 1/2”. Countersink the outboard six holes.
Click to expand...

Good analysis. This definitely needs to go in the Wiki...
 
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