Brodhead Pietenpol Association

A friend of mine was sharing some pictures of some Piet ribs (4 of them) that one whole side is a solid plywood gusset (and the bottoms on the spar passthrough looks to be for a routed spar shape). Are these reinforced ribs for the 'butt ribs' in a 3-piece wing? Nowhere in the plans do I see a call for this on a wing rib... The fact there are just 4 leads me to believe they are for the butt ribs. They also have the additional braces you would see on the two end ribs, which also isn't called for in any of three piece 3 wing plans.

Yes, those are the butt ribs. The ply sheeting keeps the ribs from deforming when the wing is covered.
The bracing in the trailing section isn't to plans, but would work just as well as what's shown in the plans.
The "cutouts" at the the spar sections are to clear the attach fittings.