I am using the RV7/RV9 service bulletin method to attach the roll bar brace to the F606 bulkhead. I modified it a little by also adding an 063 doubler under the brace. It took AN426AD4-8s to rivet the 032 spacer to the 125 angle to the 032 roll bar brace to the 063 doubler. It will take AN426AD4-10s to rivet through the top skin, top skin doubler, F606 flange, and all the previous mentioned parts. Vans service bulletin does not require a doubler underneath the roll bar brace if you use 16 AD4 rivets overall. That's the additional part I added. The service bulletin has one scenario where if you use 4 10/32 screws in place of the forward 8 rivets, you add a narrow doubler for the screws. Lets just say its very strong now. RV6 plans call for three attach rivets through the .125 angle into the vertical F606 bulkhead. I will add a 4th after I take off the top skin to allow bucking in one real tight area on that 4th hole. You can see 3 holes in the angle now.
The 032 spacer on top of the angle lowers the rollbar brace, letting window fit under topskin.
