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Date:  8-29-2006
Number of Hours:  4.50
Manual Reference:  
Brief Description:  Attempt left flap untwist and start right flap

After discovering that my left flap was twisted, I put out inquiries about the severity of the problem and possible fixes. The Vans Airforce Web blog brought out several responses. One builder said that many flaps are twisted and to "fugetaboutit". Another builder said I could drill out the rivets on the bottom of the spar, weight down the flap and re-rivet it. I called the builder's assistance help line at Vans and they told me that a 1/4" twist was not a real problem, but that they did not know how to build a straight flap. Taking the advice from the blogger, I spent considerable time and effort drilling out all of the rivets in the bottom spar. After weighting the flap down on a flat surface, I reamed the holes again (that was pretty useless since the holes were already enlarged from drilling out the rivets) and then re-riveting everything. I had to use 426AD3-4 rivets instead of 3.5 rivets because the holes were wallowed out and they needed more rivet. Well, after all was said and done, the flap was still twisted. I was only able to reduce the twist by 1/16". Instead of being 1/4" twisted, it is now 3/16" twisted. Oh well. I paused, then decided to clean up the shop and make a new beginning with the right flap. I am determined to build this one straight. I started out by attaching the ribs to the spar with clamps (I had already deburred the edges and the lightening holes of the spar, and drawn red lines down the middle of the flanges of each rib, as per the instructions). I then clecoed on the bottom skin so that the ribs would line up well with the spar. I used side clamp clecoes on the two end ribs. The inboard end rib has no locating holes on the spar, so you have to use the side clamp clecoes to locate it on the end of the spar (the end cut at an angle). Then, by lining up the red lines down the middle of the rib flanges in the holes in the spar and the bottom skin, you can then drill through the spar and th skin into the ribs, clecoing as you go. Before drilling out the bottom spar to
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Start building the flap by drawing a line down the middle of all flap rib flanges

Start building the flap by drawing a line down the middle of all flap rib flanges

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The red line is then located in the hole predrilled in the spar (look close, you will see it)

The red line is then located in the hole predrilled in the spar (look close, you will see it)

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Then the ribs are drilled to the spar and the bottom skin

Then the ribs are drilled to the spar and the bottom skin

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