Drilled holes in firewall. This is very slow work. Used Boelube and new drills but still took ages. It was awkward to hold the template in position and hold a wooden block behind the hole. I clamped the block and template where possible but there are places where I couldn't. A second pair of hands would be useful for this task. A lot of time was wasted picking off red RTV that had been used to seal the rivet heads in the firewall. You need to access those rivet heads to align the template. Wish I'd known that earlier! Got a bit blase when it came to enlarging the holes and didn't use a wooden block. Big mistake! Hit the CPU fan with the tip of the drill and broke off a piece of the plastic case. It doesn't seem to affect operation of the fan so I'll leave it alone.
Countersunk and installed nutplates on the instrument stack angles, then riveted thema nd the instument support to the panel base. Just about back where i was before I started the upgrade! Installed the txponder TX extension cable.
Drilled a new hole in the rear bulkhead flange for wires. This wasn't as easy as it looked either. Access is difficult as the drill won't fit whichever side you approach it. I drilled from the outboard side, but the lower edge of the outer flange gets in the way. Also the drill scratched the bulkead. The new hole ended up a bit too close to the existing one - should have moved it up a bit more.
