"On the Bell, if I remember it right there is a torque tube on the overhead compartment. This tube's got serrations (slits) along its axis. Overtorques twist these slits."
That torque tube on the 206 is part of the engine governor control linkage, which is connected to the collective control.
The puropose of the serrations (slits) is to allow the collective to be raised or lowered if the governor control system jams. When the system jams, this torque tube twists, allowing collective movement.