While it would not surprise me if the actual shear load in the wing bolts was reduced significantly due to the friction between the two spar pieces being bolted together, anyone who depends on the friction to hold their wings on is nuts.  You may as well use velcro.  The bolts need to be strong enough so that they can take the wing root shear and bending moments all by themselves, even if they are never subjected to that in practice due to the friction. 

As one poster stated, the loads are primarily in shear, but there's more to it than that.  The wing tries to pull forwards at high angles of attack, and air drag pushes the wing back at low angles of attack.  The shear couple between the front spar bolts and the rear spar attach fittings should be able to handle that, but some tension and compression will no doubt be introduced.  This is why we don't simply use a shear pin to hold our wings on.  Besides, if we did, they'd probably rattle, and that's not good.

As far as torque specs go, if you can't get the nominal torque (and I'm building a 360, where the geometry is different) then I'd consult Lancair and make them tell you in writing what is the minimum acceptable torque.  After all, a lawyer like Joe Bartels should understand that a verbal statement like "oh, whatever you feel like should be good enough" is not sufficient guidance for something as safety-critical as holding on the wings.

As a professional aerospace engineer I could not condone using anything less than the nominal torque without written guidance from the manufacturer.  While the FAA considers us the manufacturer, any reasonable person would place the responsibility for structural adequacy with the kit manufacturer as long as their instructions for assembly (such as bolt torque) and operating limitations (airspeed limits and load factor) are followed.

Realistically, however, if it's just not possible to torque it down that tight -- well, I haven't heard of any Legacy wings falling off yet, and that says a lot.  Still, finger-tight just isn't adequate, so there must be a minimum allowable.  Get Lancair to say what it is.

- Rob Wolf