Shim between hinge and firewall

[UnPossible]

Hey - I am planning on using screws and nutplates, as opposed to the hinges to attach my cowling. Looking at the plans, it has you sandwich a 0.020" shim between the cowl attach hinge and the firewall flange.

I am planning on making flanges out of 0.040" AL to attach the nutplates. Do I still need to add the 0.020" shim?

Thanks,
Jason

[Ralph Inkster]

The .020 shim is there to make the skin/firewall thickness the same as the cowling, so yes, put the shim in there.

[lr172]

Originally Posted by UnPossible

I am planning on making flanges out of 0.040" AL to attach the nutplates. Do I still need to add the 0.020" shim?

Thanks,
Jason

Might want to rethink that. .04" seems too thin for that application. I used .063 6061 on my 6 and do not think it was thicker than necessary. Don't forget that the bottom hinges / plate takes a real beating. 040 is definately too thin there.

Larry

[Kyle Boatright]

Originally Posted by UnPossible

Hey - I am planning on using screws and nutplates, as opposed to the hinges to attach my cowling. Looking at the plans, it has you sandwich a 0.020" shim between the cowl attach hinge and the firewall flange.

I am planning on making flanges out of 0.040" AL to attach the nutplates. Do I still need to add the 0.020" shim?

Thanks,
Jason

Your shims need to be the same thickness as your cowling flange. On my -6, I added several layers of glass on the cowling flange since I was planning to use screws/nutplates to attach the cowl. I used shim material which matched the thickness of the finished cowl edge. It has worked well over the years and provided a flush cowl/fuse intersection.