Since the wingtip is held on with hinges, I needed a method to secure the hinge pins so that they can’t come out. I fabricated these retaining blocks out of a chunk of Delrin that I machined down to fit inside the trailing edge of the wingtip rib. It’s held on by an AN509-8 screw.
The screw screws into a nutplate mounted on the back of the rib and through the tooling hole that was already present in the rib.
In the sides of the blocks, I drilled a #43 hole and machined grooves aligned with the holes to capture the hinge pins. I bent the aft ends of the hinge pins 90º so that they will go into the holes.
Here’s how they look when installed. The hinge pins can’t back out of the block because they’re trapped by the flange of the rib. The block also provides a convenient handle to extract the pins.
With those done, I primed the backside of the ribs and installed them with epoxy/flox and soft rivets.
I also sanded down the additional filler I applied yesterday. I still need to apply some filler inside the gap, but the outside shape looks great.
