by alan » Tue Oct 13, 2015 5:36 pm
OK, here's the story, shortened quite a bit.
I called Jak and he told me he was doing the first factory installation of the 13 gallon tanks designed for the Super STOL in a new Highlander build. If I would come up he would walk me through how it's done. We arrived on July 14th and got a good look how it is done on a new wing. Mounting the brackets is tough to get exactly right. The fiberglass tanks just glue to the spars. The aluminum tanks require a bracket to be aligned with the tanks in position and the brackets clamped to the tank. Tricky.
On the 22nd of July, our Highlander was stripped of its' wings and trailered to our home shop. Let the games begin! I opened up one wing and removed that tank that day. Those tanks were never intended to be removed, but this is supposed to be the short version. The hard part, before the bracket hard part, was to reshape the ribs from concave to flat bottomed. That's after removing the second rib. Remember, I have (had) the 9 gallon fiberglass tanks. The 13 gallon fiberglass was not available in 2005. I made a very thin spacer/adapter out of some marine plywood from Hobby Lobby. Actually I made 4 spacers. I also made 4 doublers to beef up those glue joints. Gluing plywood end to end and expecting it to not separate is not logical.
While I was at it I measured fairly closely the actual capacity of the tanks, old and new. Jak had mentioned that no one knew what the actual capacity was. My 9 gallon tanks held 9 gallons, give a take a pint. My new 13 gallon tanks hold 12.9 gallons, ditto.
I need to stress this part. It is vital to flush out your new tanks. While I was doing this I flushed out a ball of cuttings the size of a tennis ball. It wouldn't even come out of the tank by itself. I could kick myself for not taking a picture of it. Aside from this there were some, not a lot, of very small aluminum chips. These chips were just the right size to plug up the finger strainers.
The wing end ribs, in addition to being reshaped, now have to be modified for the relocated fuel supply fittings as well as the sight gauges. You must also replace, or reshape, the butt ribs. I replaced. It is impossible to explain how much finicky work this entails. I worked on this project 4 or 5 days a week for 5 or 6 hours a day for 10 weeks. I started on the 22nd of July and the first flight was the 2nd of October.
We hosted an EAA meeting at our shop during this process. I wanted to show everyone where the leak was. Of course, that meant I had to find it. Since the tanks were yellow/brownish already, the auto fuel stain didn't stand out. The slight stain on the inside bottom covering fabric helped zero into the area. I ended up putting a couple gallons of water in the tank and tipping it around slowly. It was coming from a flat, blank, unstained, smooth, area on the inboard side forward. Even when it was leaking it was impossible to see why.
And then there's the cover. I covered the bottom with Stits. The top requires a metal cover that is screwed down with 44 screws, each of which requires it's own riveted on nut plate. I only used 42 screws, for the obvious reason. This was a lot of work but there was no other option. My friend Don, another builder, called my Highlander a "flying Molotov Cocktail". All said, I had a lot of fun doing this, but I'm glad it's over.
I know this is a long post but I could have made it much longer. Here are some pictures.
I have lots more if anybody wants to see them.
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If I had known I would live this long I would have taken better care of myself.