I got started by priming all of the left flap components.
While the primer on the left flap was curing I got to work on the right flap.
I used my deep jaw cleco clamps to back-drill the ribs.
I marked a line .25 inches from the piano hinge edge.
I drilled the piano hinge by using the bottom skin as a guide. I used a cleco clamps and normal clecos to hold the hinge in place as I drilled.
The bottom skin was countersunk.
I installed the top skin and match drilled all holes. Not bad for a day’s work!