Wing - Left Fuel Tank

2004-02-28 - Fitting the attach angles to the baffle (5.5 Hrs).

I found Van's instructions a little confusing, and I had heard that this was a poorly written section, so I looked at Dan's website to see what he did. I found his instructions to be a little more tedious than what I though needed to be done. Like Dan, I was very concerned about getting a good match between the tank skins and the other skins, but I had already done the initial construction according to Van's instructions. So, I decided to continue with Van's instructions and see how things line-up.

First step is to turn the pile of aluminum Z-angles into T-712 tank attach brackets. This involves drilling a hole exactly in the center of each Z-angle flange. One flange gets a #30 hole, and the other gets a #12 (one bracket does not get the #12 hole). Since I didn't have a #12, I used a 3/16" drill. Later, I used the next bigger drill (13/64") to enlarge the hole in the bracket (do not use the 13/64" drill in the spar).

Then you cleco the Z-angles to the REAR of the spar, and drill the other two #12 holes from the front of the spar (I drilled the first bracket from the rear, and Van's way is a whole lot easier). Then you can remove the brackets from the spar, and attach the nutplates to the brackets.

Oh, I forgot to mention the hour-and-a-half of deburring here.

Next, attach the T-712 brackets to the FRONT of the spar using AN3 bolts. I installed all of the bolts, just to make sure that everything fit ok.
The AN3 bolts come from the rear of the spar, and are bolted into the nutplates that are riveted to the T-712 brackets.
Next, you cleco on the T-702 baffle to the T-712 brackets.
You were wondering where that T-712 bracket with only one hole went. It is the first bracket. It gets attached to nutplates that are riveted to the rear the spar. Before attaching the nutplates to the spar you need to match-drill the Z-bracket to the spar. In order to figure out where to drill the holes, you use the T-702 baffle to position the Z-bracket. Cleco the Z-bracket to the T-702 baffle, and mark the Z-bracket from the rear of the spar. Van says to drill from the back, but I defy you to get a drill in there. Just marking it from the rear, removing the Z-bracket, and drilling it on the bench works fine.
Here's the three nutplates on the other side. I have to do all of my own bucking, and I did a pretty awful job on these. The rivets are not really structural, but I think two are going to have to come out. I need to build a special bucking bar to do these blindly. In the past, I have been able to squeeze all of the nutplates.
Now, I was getting a little ansy about finding out if the tank skins were going to match the other wing skins, so I clecoed on the tank skins to see. The good news was that the top skins and all of the holes lined-up great.
The bad news was that there was a 1/8" (huge) gap between the tank skins and the leading edge skins. Of course, since there are no ribs installed, the tank skins are bent out a lot, and I am hoping that the gap between the tank and the leading edge can be pulled in. I was a little concerned, so I went to bed before I made a mistake.