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Elevator trim tab piano hinge

BoilerFlyer

Member
I have match drilled and prepared both hinges for my elevator trim tabs but I?m struggling with ?seeing? it completed. The holes on the spar are machine countersunk, but the flat hinge lays on top of them. Why then was the countersink necessary? I see a slight bulge in the skin where the piano hinge goes in between the skin and the spar and I struggle with seeing how this all comes together without some kind of countersink, which it does not call for. Am I missing something? What is the end game? Thanks everyone.
 
Hinge should be on the opposite side of the countersink

Skin on top, spar in middle (skin dimples sit in countersink), hinge on bottom.

This gives the hinge a flat surface to sit against.

Hope that is helpful. Can attach a photo if needed
 
I have match drilled and prepared both hinges for my elevator trim tabs but I?m struggling with ?seeing? it completed. The holes on the spar are machine countersunk, but the flat hinge lays on top of them. Why then was the countersink necessary? I see a slight bulge in the skin where the piano hinge goes in between the skin and the spar and I struggle with seeing how this all comes together without some kind of countersink, which it does not call for. Am I missing something? What is the end game? Thanks everyone.

As Brian said, the hinge goes underneath the spar, not underneath the skin. One suggestion that I have is to use a hand squeezer on those rivets. The pneumatic squeezer will deform the hinge if it is positioned a bit off. Also, make sure that you have the hinge pin in while setting the rivets to keep the hinge eyelets aligned.
 
Thanks for the advice Randy! I'm letting the ProSeal on the tabs cure another day so I'll sit down to rivet tomorrow likely. I have the right tools for the job and I'll keep everyone posted on how it turns out. Much appreciated as always!
 
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