(page 22-02 again) My 433rd favorite thing.....                    

...drilling out rivets.  Continuing the curse of this section, I fabricated the Firewall Spacers for step 12, did the match drilling for the Cowl Attach Plates, and proceeded to rivet these to the Lower Fuselage Assembly.  This involved squeezing some longish 1/8th inch rivets, which I have come to dread because it exacerbates a rotator cuff injury I've developed, probably from squeezing 1/8th inch rivets.  Turns out that the inboard two rivets are a problem.  The LP4-3 shop heads of the rivets which attach the tunnel ribs to the lower firewall make it impossible to square up the squeezer with the rivet.  I put the manufactured heads on the aft side of the firewall since I'm still not sure what will be visible from the cockpit.  After two failed attempts at squeezing two of the AN470AD4-5 rivets (followed by drilling the buggers out) I surrendered and drilled out the aforementioned LP4-3s, allowing a proper alignment of the Main Squeeze.  The squeezer must be absolutely 90 degrees to the surface of the aluminum.

The moral of this story is this:  When riveting the Tunnel Ribs to the Bottom Skin in step 6, don't rivet them to the lower firewall until after step 12.  This will completely avoid what I went through tonight.  The picture shows which rivets (two on each side) to hold off on until after step 12.