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   Post on Needed: KF 3 lift spar in For Sale and wanted, you got it, I want it

   By brilenz, posted 30 Apr 2021

   Looking for a kitfox 3 lift spar. Undercamber wing.  Kitfox Aircraft was going to take 6-8 weeks (which usually means 12-14...)
   If I cant find one I am going to try and build my own with Carlson extruded aluminum so any advice on that would be appreciated as well!
   Brian
   
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   Post on Lift strut repair in Technical tasks

   By whizzers, posted 10 Mar 2017

   I found a significant crack in the 5/16 thread on the top of my one lift strut. The end consists of a AN490HT 11P rod end welded around the periphery and rosette welded into a 3/4 inch x .035 tube. I doubt that I could remove the old fitting without wrecking the strut. So I carefully cut off the old threads and filed the end flat. I center drilled the end and slowly drilled it out 1/64 at a time until I came to solid metal. Turns out the I.D. of the AN490 fitting is 1/2 inch. I threaded it 9/16 National Fine, and was able to get a little over 1 inch of thread. I then made a threaded bushing 1 inch long x 9/16 o.d. with a 5/16 inside thread. Into this I inserted a 5/16 x 2 inch stud. I loc-tited the whole thing in place.
   Even a grade 2 5/16 bolt has a minimum tensile strength of 3900 pounds , and I used grade 5 at 6300 minimum. The O.D. of the AN490 is .679, giving a wall thickness of .089 at the peak of the inside threads. Maybe not the best fix but certainly the easiest.
   Give anybody heartburn?
   Bob McCaa