The nose rib reinforcement angles need to be mated to their respective nose ribs and either the flap track guide arms or deployment arms. Eight holes per assembly need to be drilled using the two pre-drilled 1/8" holes as alignment points. Plenty of Cleco angle and C clamps used to keep the alignment solid.
I then countersunk the flap track guide arms for the AN426AD4 flush rivets. This was my first opportunity to c-sink on the project so far. I really like the c-sink tool and the tight fit it creates for the flush rivet head.
Though the manual says to prime and rivet these together before drilling the spar flange end of the assembly, I elected to Cleco the whole assembly nice and tight and drill the #40 holes now. The alignment is very tight and I do not anticipate any alignment issues when riveting.
Next I Cleco'd together the entire assembly for each flap. I then match-drilled the nose rib, spar and after rib openings per the manual, up-sizing to #30 holes the rib pairs with the flap track guide and deployment arms.
Next step is to overlap the skins and match-drill them to the skeleton. I will be careful to be extra precise in this step as the nearly 9' length of the flaps can cause a ripple effect at the trailing edge or an undesirable longitudinal "twist" if not monitored closely.
