Drilling additional spar box holes?

[sbalmos]

I'll most likely call the factory about this. It's one of those things that I don't *think* would create a problem, but I'll check.

Has anyone drilled additional tubing holes in the center spar box, specifically just the aft one, other than the standard one outbound one on each side, and the two in the center? I am routing my pitot and AOA lines on the left side, which will be running up behind the center spar cap and then under the canopy deck forward to the instrument panel. But the one outboard hole in the aft bulkhead can't fit both of the lines through. I was thinking of just drilling an additional penetration right above the existing one for running the AOA line. Likewise, maybe one additional hole over on the right side somewhere (that RG-400 is relatively thick!). Opinions? Thanks.

[RV3bpilot]

I drilled about a 1/2" hole in the center of the web of the main wing spar to run my pitot hose through it. I know others have done the same. After drilling and de-burring I painted it with anti-corrosion primer.

[Jeff Vaughan]

Yes I drilled some too.
Call Vans and they will tell you where you can and can
Not drill extra holes

[airguy]

Yup, I did the same thing, I called them first and they recommended where to drill the holes, and some places to stay away from.

[sbalmos]

Yup, just got off the phone with Sterling. Boiled down to typical common sense that I figured as such. Don't nick the bars. Watch edge distances. Don't turn it the web into Swiss Cheese. Otherwise, have at it.