Today I back riveted the stiffeners, fuel drains and fuel cap housings on both tanks. This proved to be a reasonably tidy job. However! I really messed up the rivets on the right tank fuel cap housing, and I'm going to need to replace most of them. Most of the rivets are sitting proud of the skin because I obviously didn't have the skin flat on the riveting plate when I back riveted it. That's a job for tomorrow.
I also started to seal the stiffener rivets on the left tank, but ran out of the sealer mix I'd put together, so I called it a day.
