Here is the text of an Interagency Aviation Safety Alert that was issued on March 23, 2010 by the U.S. Forest Service. It describes damage to a helicopter rotor blade when someone attempted to throw a knife from inside the helicopter to someone standing nearby. Click on it to see a larger version.
The safety alert goes on to explain that a similar incident happened a few years ago when a second rocket scientist did the same thing with a set of keys. The document ends with this:
This is a repeat mistake that has been ocuring since I first started working with helicopters in the Army in 1969. Then it was a .45 pistol in a holster on a belt. It hit the main blade did major damage and resulted in the ship spinning on the ground several times. In the Everglades a few years ago a gator capture pole was put through a turning main rotor. The holder of the pole lived and the park had to buy a new set of blades for the 206. Same mistakes, just differnt people.
FYI. There has been a change to 49CFR830 NTSB mandatory reporting criteria that requires reporting of damage to main and tail rotor blades.
What is the change?
Any damage to a rotor blade is now reportable as “substantial damage”. Damage on the ground was not reportable in the past.