5 hrs, 12 rivets
I think the left tank is holding air. I added a bit of pressure last night, and it had a vacuum this morning. It's very sensitive to temperature. Today I put more pressure in, and it went up over the course of the day. It's back down below the original level now. If it goes back up the same point tomorrow then that's a take!

Installed the landing light for the left wing.

Started working on the cowl hinge pin safety/cover strips. Got one side done.
Also installed nutplates for the screws that join upper and lower cowlings behind the spinner. Countersunk, and these are ready to go.