Rib Mods Done

Time: 6 hours

Today I decided to do more research on the topic if covering up the middle hole in the second inboard rib of the fuel tanks. The lower hole has the trap door but I couldn’t find any description in the plans for covering the upper hole. I tried several searches on vansairforce.net and finally came up with one builders blog that had an email reply from Van’s Aircraft support:

20140202-191821.jpgAfter I decided that I would cover those holes I match drilled the covers to the rib and countersink them for riveting. I used flush rivets so that there wouldn’t be any chance the flop tubes could get hung up on them.

I then started the work on the anti-hang up mods for the inboard rib. The flop tube has the opportunity to get snagged or caught on the nutplates of the access plate. You can see in this photo this risk.

Van’s has you make a guide that sits proud on the nutplates like a bridge that gets riveted to the top and bottom of the access plate stiffening ring. The downside to that design is that it restricts you access through the hole as there would now be a 1/2″ wide strip of aluminum in the center of the hole. That would make using that hole in the future, should I need it, a lot tougher. Other builders have built a two piece guide that has one piece riveted to the access plate and one piece riveted to the stiffening ring. What this does is allow most of the guide to come out with the access plate and allow full access through the hole. I took my time and made several measurements to come up with a design that I was happy with.

I installed one of the flop tubes to see how it looked and fit.

With one side done I just copied the pieces for the other side, again building both wings at the same time is a great idea.

To remove the access plate you just need to slide the plate up and pull the lower portion out before pulling the top out.

It was a long day in the Hangar, I find that when I have to design and build a part from scratch it takes me a while to make sure I get it just right. I’m getting closer to the dreaded task of sealing the tanks. I ordered most of the supplies for that as well as a few more parts to make some modifications to the tanks baffles, more on that later.

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