The rudder top fairing fitted nicely with minimal adjustment, and sat squarely when pushed snuggly against the flange lip.
I decided to provide extra support for the CS4-4 Pop Rivet shop heads, since they have to be pulled against a reduced thickness of fibreglass after the holes have been countersunk to allow for dimples in the rudder skin.
I did this using NAS1149FN416P washers, bonding them with a microballoon mix. I held them in place with clecos, removing after the resin had set enough to secure the washers, but not the clecos.
Then a quick little job with the pneumatic rivet gun to set the CS4-4’s.
I want to hide the joins on the riveted fairings, so used micro balloons for the first fill …
… and fine tuning after sanding with a lightweight filler.
I used 120 grit sandpaper on a wooden block.