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Posted for "D&BWILLS" <dwills@glbelt.com>:
Good point,
I gave this some thought to this since plugging the holes was lancairs
original suggestion. Relocating and drilling the holes will put them
within 1/16" to 3/32" of the originals. I already have 6 bid base pads for
the hinge's at each location along the face of the spar. The nut plates were
mounted on G10/FR4 glass epoxy boards .062 thick, hysoled on the backside
of the spar. If I grind off the nut plates I can remove the nut plates but
not the .062 glass epoxy board they were mounted too. So I will need to
mount the nut plates onto another .062 board and hysol it over the top of
that one in effect piggy backing it. And if I'm correct the tension and
compression loads are on the top and bottom webs of the spar as the airfoil
flexes, the vertical face of the spar transmits the loads back and forth
between the top and the bottom. Maybe I should be but at this point I
haven't been as concerned about degradation to the integrity of the face of
the spar with holes that close to the original holes because this would
effectively make the holes slightly larger, even though they are not. ( I
would not use it or any airfoil that that had any holes in the top or
bottom webs this is where the loads are). My thoughts are that the flox will
be sandwiched between the .062 nut plate pads and the hinges. The thing that
concerns me most is will the bolts wobble of float over time and egg out the
holes if the hinge's are not wedged the way Larry Henney suggested in an
earlier email. I'm starting to like his suggestion.
If I'm wrong someone please correct me
Dale Wills
If I'm hearing you correctly, you have 20 extra #3 holes packed with
flox in your horizontal trailing spar. I'd suggest 5 Bid on either side
(10 Total) of the pad area to account for the spar strength degradation.
A little flox in a hole is often a good fix. In this case however the
structural integrity of your spar should be analyzed. I'd encourage you
to discuss this with Lancair.
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