The Elusive Zinc Chromate: Rebuilding Tsunamis Vertical Stabilizer

The Elusive Zinc Chromate: Rebuilding Tsunamis Vertical Stabilizer

One could argue that The Tsunami Project is neither a restoration project nor a complete rebuild of the airframe. Like I’ve said before, from Tsunamis first flight in 1986 until her last in 1991, the aircraft had been modified many times over. Some of the modifications have been well documented, while others are a bit of a mystery.

After drilling apart most of the airframe in early 2010, the first surface we attempted to rebuild was the vertical stabilizer. What we found when we took it apart, looked similar to the one pictured above. When comparing it with the drawing bellow you can see immediately that it’s missing two of the ribs.

At the time I didn’t think much of it. I knew most of the history of the plane and one of Tsunamis biggest problems early on was that it was tail heavy and that it was overbuilt, so from what I could tell two of the ribs missing wasn’t a big deal and we continued rebuilding the surface the same way we took it apart.

Fast forward 5 years – I am going back over everything we built in 2010. Unlike before when we were rebuilding the aircraft the way we took it apart, now with more knowledge of the airplanes history and more experience restoring aircraft, I try to understand what they did and why they did it, then I decide if the part should stay modified or go back to the original design. For example, when going over the timeline of Tsunami I know they attempted to lighten the tail by removing some of the less critical parts, when that didn’t give them the desired result, they ended up moving the wing back nine inches in 1989 solving the center of gravity issue.

However they never went back into the tail to replace the parts they removed. Now I am finding out that they removed more parts than I previously thought and figuring out what those parts are is easier said then done. You might be say “couldn’t you just look at the plans and figure all this out?” and ideally yes you could, but not all of Tsunamis plans are detailed, the drawing I posted above is about the extent of the plans for the vertical. The other problem with the vertical is that unlike all the other parts on the plane, where they were built in a storage facility and were well documented with albums of photos, the vertical was built in Bruce Bolands garage and I only have two pictures, one of which you can see below. That being said, rebuilding the vertical is a bit like putting together a jigsaw puzzle in a dark room without all the pieces.

Which brings me to the elusive zinc chromate! If you look at the picture below you will notice the missing primer on the front spar, now if you look closely at the picture above and compare the two, you will notice the rivets are bucked the opposite way. This was the beginning of my “ah ha” moment.

We can clearly see that pieces are missing. By using these clues along with cross referencing the vertical spar with the drawings of the horizontal spar I was able to determine with a high probability what pieces were missing.

Although this is only one example of the challenges to rebuilding Tsunami, it is a big reminder of how lucky I am to have all these many resources available to me, because without the original tooling, plans, photo albums, magazine articles and the wealth of knowledge that receive from fans and Tsunamis old crew I would never be able to rebuild this airplane.

John Bjornstad