F 1418B L and R Nutplates

Doing this work on page 10-14 now and a little confused, it doesn’t take much!

Page 10-14 says countersink the #40 holes in the 1418B L and R, nothing is mentioned about the #30 holes where the nutplates will fit.
Page 10-14 also asks for all #40 and 30 holes in the 1473 side skins to be dimpled,except where shown.

Would it be right to assume therefore that the #30 holes in the 1418B ‘s also need countersinking to accept a dimpled skin too? Or am I missing something?

Thanks in advance

Mike

You probably have everyone else (myself included) confused as well, because a nutplate is never associated with a #30 hole (they mount/rivet with #40 holes and the screw/bolt fastener hole will be #27, #19, #12, etc.).

Well you learn something every day!

I guess then I?m talking of the #27 holes instead. Do these need countersinking and dimpling?

Dimples

So not a straight forward answer unfortunately. The 2 forward most nutplates on each side do not get countersunk since they will be final drilled when the fiberglass fairing is attached. The countersink goes into the fiberglass, not the longerons or skin. You will see this on page 12-12 Figure 1 and 2.

The questionable answer is the remaining nutplates. These nutplates accept the screws from attaching the empennage gap cover (page 12-09). They are designed for the AN526C632R6 screws (which are not recessed). I personally wanted all these screws to be recessed so I countersunk the Longerons, dimpled the skin, and dimpled the empennage gap cover to accept a countersunk screw.

Up to you how you want to move forward

Many thanks Jon, very helpful. I?ll have to download chapter 12.
Mike