HS Rework SB 14-01-31 - Part 2

Today, I continued on the SB. The next step is to remove the AN470AD4 rivets that hold the ribs in place.

These could be accessed from the leading edge with a long drill bit. In general, I have been starting with a #40 drill bit to prevent damaging the holes.

This allowed me to remove the inboard ribs. First the nose ribs,

Then the aft ribs.

Next, the two angles need to be removed. These require using an angle drill to reach inside the horizontal stabilizer. I used a small square to help keep the angle drill square to the surface.

Both angles came out, and it became time to add relief notches to the spar.

My spar had no relief notch whatsoever. This probably would have ended up cracked with the stress concentration in the corner. Figure 3 in the service bulletin was throwing me off due to how it was oriented. Flipping it upside down and marking it up helped me make better sense of it.

Then, I used a cut off wheel in dremel to start the notches, and a rat tail file to finish them.

I still needed to trim back the flanges on the spar. I used a piece of wood shim between the skin and the spar to prevent cutting the skin. I used a cut-off wheel in a dremel tool for this also.

The parts were deburred the best I could.

Finally for today, I prepped the ribs. I cut off the flanges, which eliminated the miss drilled hole. I also layer out the holes for the angles that get added as part of the reassembly process. I will put things to the side for now, since I am waiting for the parts from Van’s.