Happy 4th of July! I started this morning by outlining the seatbelt bracket flange and drilling holes in the rib.

Then with the steel bracket in place (held with magnets), I positioned the aluminum bracket and back drilled through the rib.

I used the steel seatbelt bracket to act as a spacer and magnetically clamped and drilled the forward aluminum cross brackets to the ribs.

Similarly, I laid out the rivet hole locations on the bottom skin then match drilled through the skin into the aluminum bracket.

After some more fitting, cutting, filing, and drilling I've got one of the auxiliary brackets nearly completed.

I decided that at the forward end, the rib doubler wasn't doing much more than adding weight, so I decided to trim it off at the angle where it inclines to make room for the control stick lightening holes.