Today was a LOOOOONG day in the shop. To break things up a little, I am going to post in separate posts.

First, I attached a gazillion nutplates today. My rhythm is to attach six nutplates with clecos, then rivet the left ear. Remove the cleco, then rivet the right ear. Repeat until top and bottom of both left and right spars are done.

Once that was complete (1.5 hours), I got back to spar flange countersinking.

From the first issue of the 2005 RVator, page 10 (thanks to Brad Oliver from 20 years ago, for the link) and to A VAF Post (again, thanks Brad), I was able to make this cute little HTML table for you.

“We countersink until the top of the screw is level with the surface, then go 2 clicks deeper on the microstop. The actual outside diameter of the countersink measures .365″ to .375″.”

To check this, I first countersunk to flush…

I think clicked it deeper by a few clicks and verified that the resulting countersink was 0.370″ wide. Then repeated it 59 times for each flange edge.

Finally (and looking ahead), I enlarged all the tank skin attach holes to #19, deburred, and dimpled.

3.0 hours total. 1.5 booked against the ER tanks, 1.5 booked against the spars.

218 rivets set, 1 drilled out. (I’ve got my “Drill out” percentage down to 0.55%, which means on average, I’m messing up 1 out of every 181 rivets. Not bad.)

There will be more later, just breaking for lunch!