Countersinking on the rear spar assembly

[Ken Patton]

On page 14–03. In figure #2, countersinking the lower section of the W - 1207B (spar doubler plate) other than the holes required for the CS 4–4 rivet, do I go ahead and counter sink, the two outboard holes, and then counter sink the hinge bracket hole? I see those will require the CS 4–4 rivet in the next section .
Thank you for your response in advance.

 

[sc_pilot]

On page 14–03. In figure #2, countersinking the lower section of the W - 1207B (spar doubler plate) other than the holes required for the CS 4–4 rivet, do I go ahead and counter sink, the two outboard holes, and then counter sink the hinge bracket hole? I see those will require the CS 4–4 rivet in the next section .
Thank you for your response in advance.

I believe so. I didn’t have any issues going forward. My wings are completed but not fitted to fuse. Here’s a pic of mine. Note I over countersunk the outer hole. Go slow, remove cage from part and test often… I got greedy and went for it in one swoop and the shoe of the cage wasn’t as level as I thought. But I left it as is since it was tight after riveting and the countersink hole wasn’t larger than the material thickness or rivet body diameter.

 

[Bob Y]

It’s interesting that prior to November of 2018, all of the sub-spar rivets were LP4-3s, so no counter sinking required. Wonder what prompted the change?

 

[rk2436]

The LP4 head would rub on the flaperon skin. I changed mine 8 years ago.

 

[Bob Y]

Hmmm. Don’t know how much clearance I’ve got, but mine don’t rub. Guess I screwed up during my build.

 

[Tony_T]

Mine (LP4) are very close but don't rub either. This is the flaperon in the full up position. I can understand why they changed the design.