Originally the flange on an ESCO strut was held tight solely with Loctite. There was a roll pin installed, but these were more for alignment than security. If the Loctite ever failed in a shimmy event, the roll pin would simply shear. They are very brittle and are far to small too resist the forces generated by a shimmy event.
Then along came a flange brace from Lancair. This first design was the one-piece unit. The immediate drawback was that installation required removal of the flange. A long term drawback was in the design. All the torque went though a one inch weld on only on side of the unit. This was not ideal from a stiffness standpoint and cracks could develop in the weld.
Next came the two-piece brace. This was a much better design. It gripped the joint all the way around and best of all, it could be installed on a fully assembled strut.
I would encourage everyone to install one do these if it is not present. I have disassembled many struts with deteriorated Loctite where the only thing keeping the flange from rotating was the brace. When Lancair faded away I had to make a bunch of these for struts I was overhauling. I'll post something in the classified section.
Related to this is a perfect example of unintended consequences in ESCO design evolution. That flange is not screwed into the strut tube until it bottoms out. Instead it is backed off from that position a bit to allow for alignment of the hole pattern to the strut assembly. The small gap that is produced was originally taken up by an aluminum washer. Someone decided to change this to plastic. Plastic cannot resist and pass through the aircraft weight from the flange to the strut tube. Instead that load now passed though the Loctite. This accelerated the breakdown of the Loctite. Anytime I see a plastic washer, I know it is going to be very easy to remove the flange.
