Robinson helicopters are popular in New Zealand. But while they make up only 35% of New Zealand's helicopter fleet, they account for 64% of all of New Zealand's fatal accidents.
Some say the helicopter is especially prone to "mast bumping," a phenomenon where the rotor head tilts to such a degree that the rotor hub damages the mast on which on which it is attached. In Robinson helicopters, a mast bump almost always causes the rotor head and the helicopter's blades to separate from the aircraft. The result is illustrated in the video.
An article appearing this weekend in the New Zealand Herald explains the controversy and, in particular, why the unique design of the Robinson's rotor head may be to blame.