Day 88

Mounted the left wing flap & aileron today!

We had some obstacles to overcome getting them to line up though… When we riveted on the wing top skin, the manual instructed us to trim the 3.2x8mm rivets for the back of the skin where the flap would fit up against because the regular length would cause some binding issues. It was 63 rivets per wing that would have needed to be trimmed, so we opted to source some rivets that were the recommended 5.2mm, which we then used.

We had assumed these would provide enough clearance for the flap, but once we had it mounted we quickly realized that was not the case. For whatever reason, once pulled, the multi-grip rivets supplied and the ones we sourced, still have the same length once pulled. Spent some time at the rivet supply store and they had nothing that was any shorter draw. Came back and did some extensive research and found that no one carries anything that would work for us. We therefore we would have to trim the 8mm rivets we have.

We attempted a few methods to accomplish this, but each of them proved ineffective. Everything kept distorting the hole to where we were unable to replace the mandrill. We finally came up with a technique where we would pound the mandrill 3/4 of the way, use a pair of wire cutters to trim the rivet while still on the mandrill so that it wouldn’t mar the rivet hole, then remove the rivet and the cut portion of the mandrill, then replace the mandrill in the trimmed section. This was a long process. (Hence the reason we had originally tried to source them)

Next we drilled out every other rivet along the back of the top wing skin. We did this so as to make sure nothing would move from its original alignment. Then placed and pulled the rivets, then repeated the process again. We also drilled out the rest of the rivets along the back and replaced them with the 3x8mm rivets instead of the pop rivets we had used, being that they didn’t need to be the “shorter” ones and would have the rivets originally intended for them.

Once that was done, we then were able to torque the bolts holding the flap and ailerons on. We then used a straight edge to align the top and a string pulled tight across the back to align them perfectly straight.

Next we will be able to rivet the fronts of them to set their final alignment.