[DJR]

I am wanting to drill the optional holes thru the spar web as indicated on the OP-11 plans, but am a bit nervous about it. any advice before I take the plunge and start drilling.
Also, I am planning on an aft battery instal and was wondering if anyone can give me some help with the suggested aft battery cable hole and the clearance of the aileron control tube. It sure looks like the cable could interfere a bit with the suggested location.
Any pictures would be greatly appreciated for the aft battery cable routing.

Thanks

 

[Kahuna]

Here are some holes for you. And one giant one at the center control column location. A good understanding of the purpose of the spar web, will make you less nervous. Drill away. Exploded view here.