F-303H bar

I'm stumped. Does the F-303 bar attach to the spar or to the F-303 bulkhead? What is the purpose of setting its 2 rivets "double flush"?
Thanks.

Bill Newkirk,
Prather, CA

main wing spar

The 303 bar attaches to the spar web. The bar acts like a post spacer between the upper and lower spar caps.

Because it is riveted to the wing spar it has to be riveted in place "double flush" otherwise the rivets will prevent you from slipping the wing spar into the fuselage frame.

you have more to come

Fred;
Thanks for your reply. Makes sense to me.