Commercial Pilot for Rotorcraft Category Helicopter Rating › V. Takeoffs, Landings, and Go-Arounds › Task F. Shallow Approach and Running/Roll-On Landing

CH.V.F.R7

Risk management

Ground resonance.

Practice questions Ask the tutor

Study note

Get a short, cited explanation of this element written from the FAA handbooks: the core idea, the numbers that matter, common test traps, and a quick self-check.

From the FAA library

Helicopter Flying Handbook p. 11-11
Chapter 11: Helicopter Emergencies and Hazards › Ground Resonance
surface, the unbalanced condition could be further aggravated. If the rpm is low, the only corrective action to stop ground resonance is to close the throttle immediately and fully lower the collective to place the blades in low pitch ... rotor disks because there is no drag hinge. In addition, skid-type landing gear is not as prone to ground resonance as wheel-type landing gear, since the rubber tires' resonant frequency typically can match that of the spinning rotor…
Helicopter Flying Handbook p. 11-11
Chapter 11: Helicopter Emergencies and Hazards › Dynamic Rollover
rollover angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made. Figure 11-4. Ground resonance. Dynamic rollover begins when the helicopter starts to pivot laterally around its skid or wheel. For dynamic rollover…
Helicopter Flying Handbook p. G-3
Glossary
results from a reduction in upwash, downwash, and bladetip vortices, which provide a corresponding decrease in induced drag. Ground resonance. Selfexcited vibration occurring whenever the frequency of oscillation of the blades about the lead-lag axis of an articulated rotor…