What are these holes in the spar box for?

[142YX]

These holes, circled in red. I get that they line up with the alignment pin holes in the two spars, but of what use are they? they arn't used during the wing rigging process, and the alignment pins are not installed during flight. I am missing something.. why do the plans tell you to drill these holes?

[sonex892]

These holes are only used for the wing rigging, They are to pin and hold each spar in the correct position relative to each other and the fuselage during rigging. They also set the dihedral at the same time. You will need them no matter what rigging method you use.

After the wings are rigged you will never use them again.

Steve
Lazair kit 1981
Sonerai plans built 2003
Sonex 892 kit 2112

[Rick524]

I guess you dont really NEED those holes in the spar box. I updrilled the 3 holes in the spar to 1/4" and
slid screwdrivers in to keep the spars aligned when I rigged so those holes were handy. If you think you
can keep everything aligned without pinning the 3 alignment holes then go for it. The holes in the
spar box arent used later.

Rick
Sonex 524

[142YX]

I screwed up the wing pin drilling the first time.. since then i have re-built the entire spar box and i'll be doing the wing rigging operation again pretty soon now. But the first time i aligned the wings, i didn't use them at all. I pinned the spars together through the alignment holes with three short AN4 bolts which sat underneath the overhang of the spar caps.. no spar box holes required. The aft portion of the spar box is not riveted in place when you drill the wing pin holes.. so you can easily remove the short bolts after the operation is complete and before the sparbox gets riveted together.

I dont think i am going to bother drilling these holes. this time around.