Installing Cotter Pins In Drag Wire Clevis Pins

Wire braced biplanes have a lot of turnbuckles.  Usually those turnbuckles have a clevis pin attaching the turnbuckle to some bracket or fitting on the structure of the plane.  Our Fly Baby has about as many the WACO NINE.  Clevis pins are held in place with a cotter pin through the hole at the end of the clevis pin.  There is often a thin washer installed on the clevis pin, between the turnbuckle and cotter pin.

This all seems simple enough until you go to do it and find out it's all done in an awkward location, the washer falls off, and the clevis pin rotates every time you try to bend the ends of the clevis pin.

You can't always control the location and orientation to your advantage.  If you can, like working on the drag wires in the wing, position the wing so the end of the clevis pin is pointing up, or parallel to the floor.  That way gravity will help hold the washer on.

The biggest trick is to have the wire tight enough to hold the clevis pin in the turnbuckle, and stuck tight enough it can't rotate.  When you're tightening the wires you need to position the cotter pin hole in a direction to make it easy to get the pin in and bend the ends.  Some times you can just slip a piece of 0.041" safety wire through the hole to help hold it.  I have a bunch of AN416-1 Safety Pins, from my hang gliding days.  They work great.  If you forget to remove it to put in a cotter pin, the clevis pin won't come out.

To install washers and cotter pins where my big fingers don't fit, I like these Forceps.  They latch so you don't have to hold them squeezed tight like using pliers.

Grip the washer at the edge, slip it over the clevis pin, and release the forceps.

The cotter pin is just as easy to grip at the end of the loop.

Position the cotter pin so the long end will be in the easiest space to grip with pliers and to bend around the clevis pin.

I'm working with the bottom of the wing facing up so I can bend the end of the cotter pin more easily.

Hold the pin in place with the forceps, grab the long end with needle nose pliers, and wrap it around that tightly held clevis pin.  The brace wire doesn't have to be adjusted to it's finished length or tension at this point, just tight, so the pin won't rotate.  You'll go nuts otherwise.

Wrap the short end around the other side of the pin and you're done.

So Easy!