Ground resonance is a hazardous condition during touchdown or at other times when the helicopter is running while sitting on the ground. A series of shocks to the landing gear can pass through to the rotor disk and cause an imbalance in the rotor system. Under extreme conditions, the imbalance causes violent oscillations that quickly build and result in catastrophic damage of the entire airframe. While filming an episode for MacGyver this Gazelle helicopter pilot encountered the first symptoms of ground resonance and managed to recover from this potentially dangerous situation by taking off. During takeoff, the helicopters door opened in flight but the footage was kept and was aired in the episode.
