Aeroshell 22 is not the best grease for reciprocating bearings apparently. There is increased fretting of the bearing surfaces with clay based greases (which 22 is). Soap based greases perform better in this application so I use aeroshell 14 in the tail rotor feathering bearings and the main rotor flapping and lead-lag bearings. As grease can leak fom the main rotor feathering bearings and there is evidence aeroshell 14 can damage lamiflexes, the main rotor feathering bearings get 22. The fretting problem appears worst in the head bearings but doesnt seem a problem in the feathering bearings. I guess its to do with water ingress.
Everything else gets 22.
It is necessary to at least purge on changing from 22 to 14.
I dont know why soap and clay based greases dont mix, but apparently they dont.