Copilot Door Bonding

I had previously fitted and tested the door hardware and we were ready to bond the door halves. I decided to bond and fit the copilot door first to make sure there were no surprises before bonding the other door.

Amber helped me with this so we could move quickly after mixing up the epoxy.

I taped off the center latch mechanism to prevent any epoxy from getting inside. I used aluminum foil tape (with a inverted patch over the gear shaft). The reinforcements and door flange are slightly deeper than the gear box, which keeps the door skin from putting pressure on the shaft.

Amber then wet the contact surfaces while I prepared the parabeam.

We then mixed up a batch of epoxy to do the bonding. We used cabosil per the plans but we also added some flocked cotton (not as much as you would have in a typical flox mixture but enough to keep it smooth while providing some additional structure to the bond). After spreading this onto the bonding surfaces, we clecoed the door halves together (onto the fuselage) starting at the bottom and working up.

I had previously aligned the door halves to the cabin top, and pre-drilled holes for clecos, so it was easy to get the door back into the intended position.

With a bit of creative clamping, we secured the door flush to the opening surface on all sides.

The corners tended to pull away from the fuselage so we used some leverage here to pull them in.

I had previously drilled #40 holes in the center of each exterior hole in the handle area which allowed us to cleco this area together well.

I had also previously added taped aluminum backing strips to the inside of the door block areas which allowed this area to be pulled tight with clecos.

After several hours, I removed, cleaned, and reinserted each cleco. This kept them from being too difficult to remove after the epoxy cured, and allowed me to clean up the epoxy that had squeezed out on the holes between the surface of the door and the base of the cleco.

I removed the door after about 30 hours and it looks like everything bonded well. Time to start trimming and fitting..