12-24-2011:
Continued working on deburring, priming. While preparing the ribs for priming, I felt the rib to rear spar rivet hole on three of the interior ribs might have short edge margin. For a 4/32 rivet, the edge distance is only about 6/32 to 7/32. This is might ok given the load there will be low, but I went ahead adding reinforcing plate. For two of the ribs, the reinforcing plate can also serve as a shim, so there is no need for shim. Hope I can start riveting tomorrow.
The edge distance is less than 2D, it is probably ok, but I still treat it as a short edge margin issue
I fabricated a reinforcement plate as shown here. For this rib, I attached the reinforcement plate on the inside of the rib, shim is stilled needed. After this one, I realized I could attach the reinforcement on the outside and then I don't need use a shim. The reinforcement plate is made from 0.025" 2024-T3 sheet
Reinforcement plate for the rib
Reinforcement plate primed and riveted to the rib
Reinforcement plate primed and riveted to the rib
Reinforcement plate is attached to the outside of the rib on two of the three ribs showed short edge margin concern. I don't need to use shim for these two ribs.
AN470AD4 rivets are used to rivet the reinforcement plates
Bottom of the spar is countersunk, using the hinge holes as a pilot for the countersunk drill bit
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