This is three pictures of something to be aware of while locating and drilling the HS-404 aft flange and the HS-405 forward flange. The first two pictures are of the top/bottom forward most flange holes in the HS-405 where edge distance can not quite meet what is expected. The third picture is how I marked the center line of the HS-702 spar so the line could be seen through the HS-601 skin.

     

After much careful measuring, two #40 pilot holes were drilled in the forward flange of the HS-405. One was minimum edge distance, the other was an extra 1/16" due to the extra width of the HS-714. Using a 12" long #40 drill and the pilot holes in the HS-405, pilot holes were put into the HS-702 (left picture). As a perfect right angle could not be obtained for drilling all the way through the HS-710/HS-714, the HS-405 was removed prior to finishing the #40 pilot holes through the HS-710/HS-714 (center picture). The HS-405 was then re-installed and #40 clecos installed (right picture as seen from the HS-404 side).

     

The #40 pilot holes in the HS-404 (located by using minimum edge distance on the HS-404 aft flange) were used to pilot drill through the HS-702 and HS-405 (left picture). Once theses two pilot holes were drilled/cleco'd, final #30 holes were drilled from the foward side (HS-404 side) using a 12" drill bit. Since drilling from the forward side, a proper right angle to the flange could be maintained (center and right pictures).

     

All four holes were enlarged to #30 with a 12" drill bit.