Its real...its a effect called ground resonance. It occurs in helicopters that have more than two bladed heads. One blade moves out of its alignment and starts leading or lagging. This causes a gyroscopic wobble that starts to resonate due to the solid contact with the ground, eventually resulting in destruction of the helicopter. You actually dont even have to have it tied down. On some helis, even a rough landing can cause this. The only option is to takeoff immediatly, and allow it to regain stability, then set it down more gently.