Originally Posted by BobTurner
That ‘thin web’ carries the shear load which, by connecting the upper and lower spar caps (think “I beam”) makes the assembly much harder to bend. My rule is to contact Vans before drilling any non-plan holes in any part of the spar assembly.
Actually guys, the vertical shear load is taken out very near to the side of the fuselage by the attachment bolts closest to the side, which go into the parts that make up the bulkhead; F-604, F-804, etc.
Once inboard of that point, there is NO shear in the spar, it is pure bending moment -- constant bending moment. (shear is the gradient of the bending moment).
So as much as we all are reluctant to cut holes 'willy-nilly' in the shear web in the center section area, it really is not doing much but keeping everything where it is supposed to be.