I did some examination of the wing and found the cause of the failure. The main spars are attached to the center rib, and rib #4, in between C and 4 are two plywood sides that ribs 2 & 3 attach to,Neitherof them were glued to the main spars. The plywood and spars make a box for the aluminum joiner bar to slip into and I can see where the joiner was pressing against the top and bottom spars and pushed them away from the ribs. There is NO glue whatsoever on either of the plywood pieces where it met the spars, so this is clearly a manufacturing issue, and a major weak spot in the wings, especially a plane that is designed to be a sport plane where wing strength is critical.
Going to contact SIG on this and see what they will do about it. I don't want another ARF, that's for sure, but a replacement kit would be acceptable. It wont pay for the damaged servo and engine, but it would replace the destroyed plane.