W-1201A Doubler warning

[hamblin10]

Does the warning on page 17-02 make sense about protecting the LH wing spar caps from being drilled to #20 by inserting a steel strip? If you do not drill through the stack and open the holes then how are you going to install the BSPQ-5-2 rivets? Thanks!

[rvbuilder2002]

Originally Posted by hamblin10

Does the warning on page 17-02 make sense about protecting the LH wing spar caps from being drilled to #20 by inserting a steel strip? If you do not drill through the stack and open the holes then how are you going to install the BSPQ-5-2 rivets? Thanks!

The purpose of the metal protector strip is so that once the drill bit has drilled through the skins and spar flange (to enlarge the holes for the 5/32" rivets) the drill bit doesn't damage the edges of the spar cap strips that are just a bit further inside the wing.

[hamblin10]

Thanks Scott! It was just strange how it was worded about protecting between the skin and spar cap.

[rvbuilder2002]

Originally Posted by hamblin10

Thanks Scott! It was just strange how it was worded about protecting between the skin and spar cap.

In technical terms (at least in regards to our naming conventions at Van's), the spar cap is the heavy structure material (in the case of the RV-12, the laminated layers of bars) along the top and bottom edges of the spar.
The spar flange is the flanged portion of the spar channel, that the skins rivet too.

On some aircraft the spar flange and spar cap are the same thing, but that is not the case on any RV wing spar (prior to the RV-15 at least )