Incident Overview
A Hughes 269 helicopter experienced a loss of control after the pilot executed a left turn, placing the aircraft in a direct tailwind of 20 knots. The pilot reported that the engine had failed during the maneuver.
Investigation Findings
The engine was removed and run on a test stand, where no mechanical deficiencies were found. A sample of the fuel was also tested and was determined to be within specified parameters, ruling out fuel contamination as a contributing factor.
Advisory Circular Guidance
Advisory Circular AC 61-13B addresses hovering turns in windy conditions, recommending avoidance of turns downwind when winds are strong enough to limit aft cyclic control and prevent the helicopter from maintaining a selected surface reference point. The circular further notes that hovering power requires significant left pedal input to maintain heading, and that sufficient left pedal authority must be available to prevent an uncontrolled right turn once the turn begins.
Manufacturer's Operating Manual
The operator's manual for the Hughes Model 269C states that controllability has been demonstrated to be adequate in winds up to 20 mph (17.4 knots) from any direction. At the time of the incident, winds were reported from 080 degrees at 20 knots, gusting to 29 knots—exceeding the 17.4-knot threshold cited in the manual.
Conclusion
No probable cause is stated in the source.