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Date: Mon, 20 Jun 2005 09:39:08 -0400
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From: Adam Molny <Adam@ValidationPartners.com>
Subject: Re: Legacy Flap torque tube
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Thanks to all who replied to my question about torque tube binding. It
appears that there are multiple issues to consider, some of which have
been discussed here before. Here is a summary of what people said:

1) Outer flap brackets: The wing has a 3 degree dihedral. If you bolt in
the flap bracket so looks straight relative to the aft spar, it will
actually be 3 degrees off vertical, which will cause binding (the torque
tube is horizontal). One solution is to bend the bracket to align it
with the torque tube. I enlarged the slotted holes slightly, and cocked
the bracket so it sits level. This makes it appear crooked relative to
the spar, but that shouldn't hurt anything.

2) The sides of the center console are not vertical, so when you install
the bearing blocks, they cock relative to the torque tube, causing
binding. Smarter people than me planned ahead and did a flox release
between the bearing block and the center console to create a flat
mounting surface. I had already drilled my holes and installed
nutplates. I ended up shimming out the four corners with various numbers
of thick and thin washers to get the alignment right. This is less
desirable because it is a pain getting all those washers installed
without dropping them, and you have to make a record of which quantities
of washers go where.

3) Lastly, I spoke with Justin at Lancair. It turns out that some torque
tubes were welded out of tolerance! I believe that in my case, the
circular end plate is not centered on the tube. With the two halves
bolted together and the left bearing block installed, the right side
moves through an elliptical path This means that it is physically
impossible to align the bearing blocks for smooth operation. Justin is
sending me new torque tubes, and I have to send back the old ones.

Finally, greasing the bearing blocks helps quite a bit. You would think
the teflon is already slippery enough, but a little axle grease makes a
big difference.

Thanks again for all your input.
Sincerely,
Adam Molny
Legacy #151