FGD135 said:
"There is a third regime, and that is: windmilling-prop. In terms of flight characteristics, this one is like a more extreme version of flight-idle."
Very clear... And agree...
Additionally, this much more grave situation would not necessarily be limited to a failure of any sort...
It could even happen if the flight idle rigging for an engine-propellor combination, for whatever reason, would be incorrect (too low)...
Kind regards, learner...