It's always fun until it isn't anymore. This helicopter crew finds out the hard way as a low-level buzz results in a condition known as servo control transparency. This happens when the aerodynamic forces in a helicopter rotor system exceed the maximum force produced by hydraulic servo actuators. It happens most often when pilots attempt particularly aggressive manoeuvres. The result is a pitch up and roll toward the retreating rotor blade, which proved to be disastrous in the case shown in this video. Everyone was lucky to walk away from this one.