REFLECTOR: old box spar question

[doug.holub at tx.rr.com]

I have a question for anybody out there with an old box spar: There are bulkheads inside the spar just outboard of the inboard wing attach bolts. As I understand it, the bolt access holes at the bottom ends of the main spar are used to suck air out of the cabin. Am I supposed to cut a hole in the spar bulkheads to let the cabin air escape?

Doug Holub