So I made a mistake ... I followed the drawings to the milimiter ! Probbaly to close ... Here is what happened : I placed the rib of station 83,5 at exactly 83,5 inches but forgot to check if the bolt holes were also align with the center of the rib flange .... and guess what .... they were not ! Meaning the center of the bolt holes were not at 83,5 plus 5/16" .... 83 13/16"
I wrote to Vans but I think the fix will be to replace the 2 ribs flanges (main & leading edge) with an angle of 1 X 1 which will give me the required 1/4" I need to get the bolt hole far enough from the angle vertical wall.
Lesson learned ....
Problem: bolt holes too close to angle
this is the error from the spar view
View of the pilot hole in the angle and the rib flange in front