Each end of a flaperon gets a root rib, a full rib or a tip. A full rib is placed on the each of the “internal” ends, where the inboard and outboard flaperons join. The root rib gets attached to the fuselage end on an inboard rib, and the tip goes on the outboard end of the outboard flaperons.
Still working on just the passenger side inboard flaperon, I cleco’d both ribs to their respective ends, using the plans to make sure I got the right positions; the root rib is made of a thicker material than the full rib, presumably since it has a greater load being attached to the fuselage.
With both ribs in place I opened up all the holes in both sides of the skin to size 30 for an A4 rivet.
An angle bracket gets attached to both the spar and the rib, the positions of the holes for the full rib are given in the plans.
This is then used to locate the drill holes on the spar and the rib and these are drilled out for an A4 rivet and after some deburring and priming, I riveted the bracket to the rib. The instructions call for riveting the bracket to the spar but this is clearly wrong since it would then be impossible to remove the spar from the skin for later deburring.
The root rib gets a control horn attached and this is strengthened by cutting and riveting an L-angle behind it and to the rib and through the spar.
The pilot holes in the horn get enlarged to size 20 for A5 rivets. Two of the holes in the plate go through the rib and into the spar via the angle bracket. I made the mistake of pre-drilling the holes in the angle bracket to the same spec as the full rib but realised later that the position of the holes in the control horn will determine the actual angle bracket location.