Dynamic rollover occurs when excessive lateral angular momentum is created around a pivot point.

Dynamic rollover occurs when excessive lateral angular momentum is created around a pivot point.

• A. Ground resonance
• B. Vortex Ring State
• C. Tail rotor failure
• D. Dynamic rollover

Answer: (D)

Dynamic rollover is a situation where a helicopter tips and then rolls about a pivot point on the ground, driven by a growing lateral angular momentum around that pivot. When the helicopter is perched on a skid or the edge of a surface, a side-to-side rolling moment can cause the rotor’s lift to propel the fuselage to rotate about that contact point. If the pivot remains and the lateral momentum isn’t interrupted—by easing cyclic input, shifting weight, or breaking contact—the roll can accelerate into a full rollover. The essence is that the danger comes from building up and maintaining lateral angular momentum about a ground pivot, which is exactly what dynamic rollover describes. Ground resonance is a vibration of the airframe that occurs after contact with the ground when the rotor is still turning, not a rollover about a pivot. Vortex Ring State is a descent state where rotor wash recirculates in the rotor disk, causing loss of lift, not a pivot-based rollover. Tail rotor failure removes anti-torque/yaw control and can lead to uncontrolled yaw or spin, not a rollover about a ground pivot.

Dynamic rollover is a situation where a helicopter tips and then rolls about a pivot point on the ground, driven by a growing lateral angular momentum around that pivot. When the helicopter is perched on a skid or the edge of a surface, a side-to-side rolling moment can cause the rotor’s lift to propel the fuselage to rotate about that contact point. If the pivot remains and the lateral momentum isn’t interrupted—by easing cyclic input, shifting weight, or breaking contact—the roll can accelerate into a full rollover. The essence is that the danger comes from building up and maintaining lateral angular momentum about a ground pivot, which is exactly what dynamic rollover describes.

Ground resonance is a vibration of the airframe that occurs after contact with the ground when the rotor is still turning, not a rollover about a pivot. Vortex Ring State is a descent state where rotor wash recirculates in the rotor disk, causing loss of lift, not a pivot-based rollover. Tail rotor failure removes anti-torque/yaw control and can lead to uncontrolled yaw or spin, not a rollover about a ground pivot.