Countersinking nutplate holes on spar

[CaptPausert]

I went to countersink the nutplate attach holes on the spar today and found that the pilot of my #40 counterskink cutter is slightly too large to fit in the hole. Tested the hole diameters with a -3 rivet and it fits very snug no slop at all.

Is it normal to have to ream out the spar holes to a #40 prior to countersinking? It doesn't say in the instructions and wanted to check before I do anything to the spars

 

[skelrad]

I can't remember about the spars specifically, but most holes in the 9A aren't final size, so you need to do all of your match drilling or final size drilling first and then finish with your countersinking or dimpling.

 

[GeoffP]

I'm fairly sure I had to run a #40 reamer through the nutplate holes on my spars. I put it down to the anodizing, but that may not be the reason since all other nutplate rivet holes in a -9 kit need to be reamed also.

 

[CaptPausert]

Thanks just wanted to make sure before I touched the spars. Really dont want to make any mistakes on those.