Have been in "setteling with power" in a Hughes 269A (not a fun aircraft to teach it in as the vibration level puts the viewable world out of focus), a two bladed Bell and, a CH-47.
Have done it at 3000' and 13,500'. I'm not an expert but, my position differs with some.
If you are going down with no power applied and no forward airspeed and you don't feel too badley about it all, you are in a descent.
If in the descent, you apply up collective or forward TCL and stall the inner/slower portion of the rotor system where some air direction has already been up, you increase the stalled area where the second (at the inner portion of the rotor system) Vortex Ring has been for as long as the air has been going up through the rotor system instead of down and, you now feel very badley about it all, you are in setteling with power. More power/pitch, larger area where the air is going up rather than down meaning more of the blade is effectively stalled and not performing. Point being, you may be able to get the aircraft to go down fast enough to get a flow of air up through the rotor system near a the center/slower downward flow area. But, you are not "setteling with power, in my humble opinion till you make the mistake of increasing the power/pitch and increase all that has been only a potential bad thing to this point. When the pitch of the blade increases at the root, it increases at the tip. Which means it creates more/faster downflow of air until it exceeds design limit.
Recovery: correct what got you here. Forward airspeed and reduce power/pitch till the rate of descent slows noticably and the vibrations smoothe out. Then add power to stop the descent and fly out. Adjust as necessary for nearness to the ground. In a tandem rotor aircraft give thought to going to the side to find the clean air for the rotor system as forward or aft cyclic will only keep one of the rotor systems in setteling with power while the other has reverted to vortex ring state when the power/pitch was reduced. Two rotors fore and aft or lateral makes no no difference. The rotors don't know they have a twin, they stall/recover as individuals.
[This message has been edited by VLift (edited 22 January 2001).]
[This message has been edited by VLift (edited 22 January 2001).]