[cayuse]

People have been seriously injured and even killed by being struck by rotor blades when they come off in a crash or some other component failure.
I never fly in public parks anymore since stray dogs and 5-year-olds tend to come out of the woodwork and chase the heli around, completely oblivious to the risk. I fly my heli indoors at work (large warehouse space) or at my club field, where everyone knows the risks and stays clear.