After all the opinions expressed on this thread (mine included ), I am convinced that the only solution is to box in the spar caps by installing a shear web on the front and aft sides of the spar - one horizontal grain and one vertical..

Better yet, make 'em out of .125 inch titanium with stainless steel rivets holding them together and we'll have no more failures... Of course, the airplane will be too heavy to fly, but hey - no failures!!

Can we get a quorum to declare this horse officially dead, or do we need to beat it some more?

Cheers!

Jim