On September 4, 2004, a Robinson R22 BETA (registration N176FM) operated by Aviane was involved in an aviation accident near St. Thomas. Investigators recorded the probable cause as: The investigation identified a fracture in the tail rotor drive shaft exhibiting evidence of torsional twisting, which contributed to the loss of directional control. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced an uncontrollable right yaw during takeoff from a marina dock, resulting in an emergency autorotation into the water.
What happened
The pilot was operating a Robinson R2CO (registration not provided) parked on a dock at the Crown Bay Marina with a northeasterly heading. After starting the engine, the pilot performed a right pedal turn and established a 4-foot hover with normal engine indications. The pilot then began a southeasterly takeoff profile into a 10 to 15 knot wind, maintaining a steady climb at 30 to 40 knots.
At an altitude of approximately 20 feet, the helicopter experienced a sharp yaw to the right. Although the pilot was able to correct the heading using left anti-torque pedal input, the aircraft subsequently began spinning to the right uncontrollably. The pilot initiated an autorotation into the water. Both the pilot and the passenger were not injured and successfully evacuated the aircraft before it sank approximately 60 yards from the dock. The pilot reported that no objects were struck during the flight.
The investigation
A Federal Aviation Administration (FAA) inspector examined the tail rotor and discovered that the tail rotor drive shaft was fractured approximately six inches aft of the tail rotor drive shaft damper assembly. An NTSB review of photographs provided by the FAA showed that both fracture surfaces of the tail rotor drive shaft exhibited evidence of torsional twisting. Additionally, the tail rotor blades were found to be fractured approximately 8 inches from the center of rotation.
Probable cause
The investigation identified a fracture in the tail rotor drive shaft exhibiting evidence of torsional twisting, which contributed to the loss of directional control.