FAA Private Pilot Helicopter (PRH)Performance and LimitationsHard
A pilot is operating in a high hover with a high power setting and a low forward airspeed when the helicopter begins an uncommanded rapid descent despite increasing collective. This is characteristic of
- Alow rotor RPM (blade stall)
- Bretreating blade stall
- Csettling with power (vortex ring state)
- Ddynamic rollover
Show answer & explanationAnswer & explanation
Correct answer: C. settling with power (vortex ring state)
Settling with power, also known as vortex ring state, occurs when the helicopter descends into its own downwash at low airspeed and high power, causing an uncommanded increase in rate of descent that cannot be arrested by increasing collective alone; recovery requires reducing collective and gaining forward airspeed or altering the flight path.
Why the other options are wrong
- A. Low rotor RPM blade stall involves loss of rotor speed, not specifically descent into rotor downwash.
- B. Retreating blade stall occurs at high forward airspeeds, not in a low-airspeed hover situation.
- D. Dynamic rollover involves a pivoting motion on the ground, not an in-flight descent.
Settling with Power (Vortex Ring State)
A condition where the helicopter descends into its own rotor downwash at low airspeed and high power, causing an uncontrollable increase in rate of descent.
- Occurs with low airspeed, high power, and high rate of descent
- Recovery requires reducing collective, applying forward cyclic, and gaining airspeed
- Increasing collective alone worsens the condition
Memory trick: Sinking into your own storm — add power and you just sink faster.