Waiting for drywall compound, aka "mud," to dry means that I needed to find something else to do for a while. The F-319 (or it might be F-317 or F-318, it's called all of those. But on drawing 22, it's F-319) aft deck was cut out a while ago but not drilled for installation. It's intended to be riveted to the longerons and the F-309 bulkhead. On my plane, it'll be attached with screws so that I can remove it for access to the area.
I measured where the holes should be and marked some to avoid drilling until later, just in case the horizontal stabilizer blocks a portion. Then since the .040 aft deck was opaque and I couldn't verify the longerons under it, I overlaid a bit of that .030 Lexan that I'm using as patterns and transferred the hole locates to that. Placing it over the longerons, it was obvious that I needed to shift the hole locations just a bit outboard for better edge distance. No problem, since I could see exactly where to put them.
The .030 Lexan is sourced at McMaster. It comes with a matt plastic protective layer, much like the blue vinyl we enjoy so much, except that it's translucent. It easily holds the Sharpie marks and the sheet is stiff enough that It makes superb patterns.
Once the Lexan template was overlaid on the aft deck, I used my handy Verits optical hole punch to punch through the Lexan into the aft deck. The next step was to drill the holes to #50. Why #50? Because that's small enough that if necessary, I can walk the hole to a slightly better location, and also because a Sharpie just fits and I was able to mark the longerons with the hole locations.
Removing the aft deck, I checked the hole locations on the longerons and verified that they were acceptable. Then I pilot-drilled through both the aft deck and the longerons with a #4The large access holes still need to be made.
The large access holes still need to be made.
You might notice a small part at the forward left of the deck at the bulkhead. That's an oopsie. I'd drilled a hole for the OAT sensor in the wrong location and that conflicted with where the screw hole needed to be on the aft deck. I made this small part to get to a better spot. After the photo was taken, I trimmed the part to make it smaller. You can see the new OAT hole above it on the bulkhead.
The mud is coming along nicely. It's just slow, is all, in case you were wondering.