On May 27, 1984, a Bell 206B (registration N102CD) operated by Chaparral Aviation was involved in an aviation accident near San Antonio, TX. Investigators recorded the probable cause as: The pilot's failure to maintain control during a left orbit while operating out of ground effect at low airspeed. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 10 related events involving the same aircraft type or operator are linked below.
A helicopter yawed uncontrollably to the right while operating out of ground effect at low airspeed, leading to a crash with no mechanical failures found.
What happened
The incident occurred while the helicopter was executing a left orbit maneuver. During this phase of flight, the aircraft experienced an uncommanded yaw to the right, which continued into a full right rotation until the helicopter impacted the ground. At the time control was lost, the aircraft was operating out of ground effect at an altitude of 250 feet above ground level (AGL). The environmental conditions included a density altitude of 3,751 feet and an indicated airspeed between 20 and 25 knots. Despite attempts by the pilot to regain control of the aircraft, these efforts were unsuccessful.
The investigation
Examination of the wreckage revealed no evidence of mechanical malfunctions or failures that would have contributed to the loss of control.
Probable cause
The pilot's failure to maintain control during a left orbit while operating out of ground effect at low airspeed.