A section of the helicopter’s rotor blade undergoing examination by accident investigators.
A pilot and flight engineer were conducting multiple autorotations during a flight test of developmental blades in an experimental Bell 206B when the main rotor head separated from the mast and the helicopter fell to the ground, the U.S. National Transportation Safety Board (NTSB) says.
The 1,200-hour pilot and the flight engineer, who was an aeronautical engineer and a private pilot, were killed in the April 16, 2019, crash in Fort McDowell, Arizona, U.S., and the helicopter was destroyed.
In its final report, the NTSB said the probable cause of the accident was the separation of the main rotor head following “a sudden displacement of the cyclic stick during a low-G maneuver, leading to mast-bumping” – contact between an inner part of a main rotor blade or a rotor hub and the main rotor drive shaft (the mast).
The report cited as contributing factors the “unsecure p…
