Match drill replacment ribs 5

As determined previously, the side skins were used as the template for the match drilling process. The match drilling was done in this manner only as far back as the CF-ANG-006 holes. The reason for this is that the rib 5 takes on a slight bend aft of this location and thereby shifts slightly relative to the skin compared to the relationship when lying flat. All the match drilling was done in stages, as usual, starting with a 1/6" drill, then a 2.5mm drill to fine tune the centering, then 3.3mm reaming with further fine tuning. 4mm holes were finished off with a 4.1mm reamer, and 4.9mm holes were finished off with a 4.9mm reamer after an intermediate step of reaming also to 4.1mm. The final match reaming of seat belt mounting holes to 4.9mm was deferred until the skins and ribs were fully clecoed in place and hole alignment confirmed. Two of the seven holes were match reamed from the inside using the skin holes as a reference. The remaining holes were match reamed from the outside using the seat belt mounting bracket, now clecoed in place and aligned, as a reference.

Both left and right ribs 5 upsized in this way. A perfect alignment was achieved. 4mm and 4.8mm rivets could be inserted freely, or with at most a cleaning final ream at the 0.05mm level.