Pitts cabane stiffener
The Pitts had a cabane stiffener that was mounted on the upper wing attach bolts. It consisted of two 1/2" tubes welded to plates on each end that butt up against the inside wing attach brackets. Because the bolts are above the bottom of the airfoil, the tubes were curved slightly to keep from touching the bottom of the wing. It may have been sufficient for stiffening up the rear cabane, but it seemed like on odd part that was a non standard solution to a known issue.
Today, I fit a new stiffener made from 5/8" X .035 4130 and welded it near the top on the left side of the cabane. This is the solution I'm familiar with, though I've seen a variety of tubing sizes used. The new stiffener is without a doubt superior to the old part. It is out of the way when installing the fuel tank and also opens up access to the wing tank vent and flop tube connections. Installing the fittings for the wing tank was a real chore with the old part in place.
I also did some prep work on the backup lap belt mounts. They need to be moved lower and further back than their current location. The Hooker lap belts are a little too long and I use up most of the adjustment getting the second belt snug. I ran out of time to do the welds, but that should just take a few minutes when I get out there this weekend.
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