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My IA raised a question during the inspection of the plane, about the attachment fittings where the wing spars bolt onto the fuselage. There is room for the wing to move forward or back, because the fittings are larger than the spars. Should one of those connections have shims to prevent movement? and if so: Which one (FWD or AFT fitting)? and should the wing be shimmed fully forward, fully aft, or centred?
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The aft fitting was left intentionally a bit bigger so scratch built wings would fit on our fuselages. You could put washers in the gaps if you wanted. I will ask Bob Barrows your question when I talk with him next. This is really a Bob Barrows/engineering type question. Mark -
Bob said nothing is really needed because of the way the load is on these wings - only one direction. You could put a washer in the aft fitting if the gap was big if you want. But not required. The only reason to put a washer in there is so you can tighten slightly the bolt/nut. But you do not want to over tighten that nut so the upper longeron attach fittings bend. MarkComment
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If the front attachment is snug then it should be no issues as the wing cannot move for & aft. A lot of shaft designs are set up so that one point on a shaft is locked and the second point floats. The attach points are on the same axis so one tight and one loose should be no issue as long as the bolt fit through the fitting holes are snug. Snug the rear bolt up like a spark plug hand tight and then tighten gently with a wrench and that is safe. We set the wing attach fittings up with the front tight and some clearance in the rear. As long as the hinge is tight then there are no issues. If it bothers you or you need to satisfy the inspector you could check the clearances with feeler gauge & purchase some SS shim stock.
Glenn
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