Sect 10-11, Steps 1 & 2: worked on the two larger forward Bulkheads....doing all the #40 hole dimples around the flanges...with a few exceptions noted.
Lots of lightening holes which take time to smooth edges/deburr. Tried various tools (eg dremel to reach inside holes) but mostly the std 6" grinder w/ scotchbrite wheel. Although instructions don't denote, I smoothed facets of flanges...just as prior bulkheads. Finding a 4" belt /6" disc sander with fine grit paper works well for that step.
Also enlarged one hole to 5/8" hole w/ step drill...for bushing w/ wire routing. Seems odd several similar 5/8" holes already pre-punched - must be busy work for builder wrt 51% rule...?