The plans call for the fabrication of 2x W-00009A Wing Box J-Channel – Long (sometime called J-Stiffeners as well) and 2x W-00009B Wing Box J-Channel – Short. As a matter of fact, this is just for the left wing. You have to double this for the right wing as well. At first, I thought they had to be revited to the spar but then I saw further down in the manual that these are stiffeners for the top and bottom skins. Nothing to do with the spars themselves. The spar flange are smply used as a drilling "jig" for the stiffeners. I figure this is an elegant (and perhaps less risky) way to “pre-drill” them without doing this with the fragile skins. The less you play with them, the better.
W-00009B is to be cut at 73 9/32 in. Gush... that is precise. There must be a reason that I fail to know for the moment but let’s do it as per the plan’s call. Judging from photo #2, I guess it is quite close to 73 9/32 in... Also, I have buddle them in order fabricated them all the same length. I trust my skills to make the cut at the right length but this is risky If you screw up, you screw them all up!
There’s a note on the plans that specifies to NOT match-drill the lower wing box j-channels in the three areas on the lower spar flange. To keep me from making a mistake, I’ve covered those holes with masking tape (isn’t it for that purpose this tape exist ?) so I’ll know exactly where to NOT MATCH DRILL.I took this precaution after reading on VAF that few guys drilled off some of these holes by mistake. It won’t harm the main spar but it will give you some trouble at the time of clecoing the skins; few holes won’t match. You’ll have to make a doubler to fix this.
