I literally stared at a single hole on HS-00001 for about an hour this night. Why you may ask???? The dreaded minimum edge distance rule. What is this rule you speak? Look it up if you're not familiar, basically for a protruding head rivet, you want at least 2 times the diameter of the hole (from the center) to the edge of the surface that is being riveted. Makes sense as not having enough material surrounding a rivet is asking for a stress crack to start.

The plans call for you to make a relief notch in this part of the spar half HS702 to try to prevent stress cracking from occurring. This is what prompted Service Bulletin 14-01-31 in the first place. The plans call for you to notch this hole right on the bend line in the corner of the spar webbing. The plans want you to make this hole 1/4" in diameter centered 5/16" from the edge of the spar. If you make this relief hole exactly as the plans call out, you will not have enough edge distance for one hole on the top of the spar/doubler combination on each half. Look at the picture to see what I'm referring to. I've drawn the approximate shape of the hole and you can see as drawn, at best you may have 1.5 diameters from the center of that whole.

Now some builders may argue what's the big deal and maybe they are right but if you go searching online this topic comes up quite a bit among builders trying to do the right thing the first time and trying not to have to repeat the step after they screw it up.

So what's the solution? The leading solution seems to be to just make the relief notch just slightly smaller for these two relief holes than what Van's calls for. The idea of the relief notch is to spread the stress so that it doesn't lead to a crack. A notch slightly smaller than the plans call for will still give you the same result and also assure your minimum edge distance is maintained.

So next time out in the shop I will cut these notches and bend the tab of each spar to the called for 6 degrees. I might even bend them the correct direction the first time through..... Time for Christmas 2020, a Christmas like no other so time to take a break from the build for a few days.