Final Report: AS 350 tail rotor separated
Eurocopter AS 350BA, Kapaau, Hawaii, July 12, 2005–The NTSB blamed the crash of the AS 350 on the in-flight separation of the tail-rotor system as a result of a loss of clamp force and fatigue fracturing of the attachment nut plates, likely due to a tail-rotor blade strike during a landing. This resulted in an imbalance and a high-frequency vibration that induced fatigue in the nut plates and caused one bolt to back out.
After takeoff, at about 500 feet at 90 knots, the pilot said he felt a high-frequency vibration, then heard a “bang.” The helicopter violently rolled left and pitched nose down, and rolled over to the right. The pilot recovered and landed, uninjured