Mix and Match wing spar parts

[bret]

I bought a QB wing here and came to realize I need a Center Section for the fuse kit, I found one on here also but was concerned about the CT bolt fit, I heard that the parts are CNC machined but still, why would they need your CS for the wing kit? so anyway I test fit the parts with grade 8 hardware bolts today and no problem.

[rvbuilder2002]

Bret,
It is because of the evolution that RV kit production has gone through over the years.
At the beginning of RV-8 production (and maybe even a period with the RV-9 also), the production tolerances were not as tight with the processes being used, as they are now. So center sections and spars were always kept together as a matched set.
That is no longer the case, but it is still possible that if someone purchased just a portion of an older used kit and paired it with a different kit, that some of the holes would have a slight misalignment.

[pierre smith]

Bret, the older -4 and -6 kits had a matched assembly, the center section and spars were drilled as dedicated-to-each-other assemblies and the wings were sent out with the center section for the fuselage.

Nowadays, with all Van's CNC machining, It's my understanding that the units are so accurate that any center section and pair of wings will fit on the newer -7, -8, -9 and -10 airplanes.

Best,

[airguy]

Just a couple years ago Vans had a production problem with the main wing spars on the 9's, with the flanges bent incorrectly (mine were affected). They exchanged the affected spars with new correct ones, and they mated up perfectly with the existing center section. I was a bit concerned about the match as well, since my original set were all marked with the same production number - but Vans told me not to worry, it would fit - and indeed it did.