Brief Description: Drill wing attach 5/16 bolt holes to fit NAS bolts
1. As noted on 7/9/10, the new NAS bolts in the upgrade kit were a bit loose in the first two holes that I reamed in the spar root doubler with a 0.3125" reamer. The bolt shafts measured 0.3085" diameter so I ordered a 0.293x0.309" reamer from Brown Tool to ream the remainder of the holes.
2. My procedures was as follows. I had previously drilled 0.125" pilot holes based on the transfer punch.
3. I bolted the doubler plat to the spar using AN4 bolts and hardware store 1/4"x28 nuts to assure alignment of the doubler to the holes reamed in the spar cap.
4. Using my drill press as shown previously, I enlarged the 0.125" pilot holes in the doubler to 3/16", 1/4", and to 19/64".
5. Then I used the new reamer in the drill press to bring the holes to final diameter. The bolts were quite tight in the 4 reamed holes. It will be interesting to see if they can pass the bolts when they wing spar is mated to the center spar.
6. There is a pronounced kink in the bottom spar cap at the location of the doubler that I used to reinforce the (dented area of) the web. The kink caused the spar cap to be angled upward on the jig. To force the drill bit to be normal to the spar caps, I used a clamp as shown in Fig. 1 to hold the spar cap tightly against the jig. The kink is shown in Fig. 2. The kink is much less pronounced in the top spar cap, most likely because the extruded angle doesn't bend easily. I will send these photos to Zenair to get an opinion on whether the kink is a structural problem.
