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Countersinking on F-10418B-L&R page 10-14

Yank

Active Member
On page 10-14 step 2 it has you countersink the #40 holes in the longerons to fit dimpled skin... got it... what about the #40 holes for the nutplates? On page 10-20 there is a note that says ?nutplates installed on the longeron are not dimpled. I am assuming that they are referring to the #27 screw holes and not the #40 nutplate rivet attach holes.... confused as usual....
 
I found this section very confusing. Figured out when they say the nut plates are not dimpled it means the nut plate holes that -3 rivets go though are not dimpled. Has nothing to do with the screw hole. They are not dimpled because the longhorn is thick enough that the tapered portion of the rivet head doesn't go in that far.
 
Do you still need to countersink the #40 holes in the longeron to accept the AN426-A3-4 rivets used to secure the nutplates called for in figure 1 page 10-20 step 3? Completely confused...
 
My take

The way I read it... The nutplate holes on the nutplates themselves are not dimpled as the inner face of the longeron is flat where these nutplates will be seated. The remaining nutplates common to the bulkheads need to fit a dimpled hole and need to be dimpled as well.
 
I did not do that part yet and I am not at the plane. If what the nut plate is mounting to is dimpled than the rivet holes in the nut plate should be dimpled. This is a general rule. In the case of the longerons they are thick enough and are not dimpled.
 
The way I read it... The nutplate holes on the nutplates themselves are not dimpled as the inner face of the longeron is flat where these nutplates will be seated. The remaining nutplates common to the bulkheads need to fit a dimpled hole and need to be dimpled as well.

Yes correct.
 
Hmmm.

Not at the plane so can?t look at it but ponder this...

Looking at the plans it appears the rivets that hold the nutplates onto the longeron go through the skin, then through the longeron and then through the nutplate attach holeS. So the nutplate attach holes in the skin are dimpled and nest into the countersunk holes in the longeron. Therefore the longeron is ?sandwiched? between the skin and the nutplate. The screw holes are not dimpled. Those screws hold the empennage gap covers in place (see section 12 page 12-09)

Here is a picture from my build:

A2941-DA6-6289-4-AD4-9-C12-B022-C93326-A8.jpg
 
Rudder cable penetrators

Not at the plane so can?t look at it but ponder this...

Looking at the plans it appears the rivets that hold the nutplates onto the longeron go through the skin, then through the longeron and then through the nutplate attach holeS. So the nutplate attach holes in the skin are dimpled and nest into the countersunk holes in the longeron. Therefore the longeron is ?sandwiched? between the skin and the nutplate. The screw holes are not dimpled. Those screws hold the empennage gap covers in place (see section 12 page 12-09)

Here is a picture from my build:

A2941-DA6-6289-4-AD4-9-C12-B022-C93326-A8.jpg


Where did you acquire your rudder cable penetrator aerodynamic guides?
If that's what they are called. My supplier guides are a few Teflon blocks but I like yours a lot more.
 
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