The S-300C has a four cylinder Lycoming HIO-360-D1A engine.
Engine rpm green arc sits around 3200 rpms.
Why is
exceeding 2000 rpm without load considered overspeeding?
FM:
IF ENGINE RPM EXCEEDS 2000 RPM WITH
ROTOR DISENGAGED INSPECTION OF DRIVE SHAFT
IN ACCORDANCE WITH HMI APPENDIX B IS
REQUIRED BEFORE ANY FURTHER OPERATION
What engine parts might be damaged?
I find that very astonishing, considering that all cams, crank and shafts are built for sustained 3200 rpm;
and I do like to understand the reason for a rule, helps memorizing it a lot.