I'm not sure what made me notice these, but just outboard of several of the outboard-most rivets on the bottom skin, I noticed what looked like fine scratches. They're too fine for my eyes to see well, but the fact that they're pretty closely aligned with the side of the fuselage side skin gave me a sinking feeling that they may be cracks rather than scratches.

To get a better look, I bought a cheap-o wifi microscope on Amazon.

Unfortunately, I was right. I do, indeed, have cracks at these locations. I'm going to have to figure out what I want to do about this.

In the meantime, I decided to add one more nutplate to fasten in the aft edge of the right side interior side panel.

Installed.

I also decided that the I wanted to roughty double up on the number of screws attaching the baggage bulkhead corrugated cover and the aft flanges of the baggage floor pans to the F-706 bulkhead. Way back in the day, I had converted every 4th pop rivet hole to a #8 screw. I decided to change that to using a screw at every other pop rivet hole.

At this location, I needed to drill in between two pop rivet holes rather than just drilling and existing hole up to #18. So, I made a little drilling jig so I could drill the same location on the aft flange of the baggage floor pan...

...as on the F-706 bulkhead itself.

At the other locations where I was drilling up a prepunched hole to #18, I just fitted the floor pan to the F-706 and match drilled.

Then all these new #18 holes had the appropriate nutplate rivet locations drilled. I installed all the nutplates (no photo of that, sorry) except for one. I need one more single lug nutplate (MS21051-L08) which I can dimple. I have a couple, but they have ribs formed along the sides of the middle hole which will be a problem for dimpling. I ordered more of these nutplates.