Eurocopter AS 350B3 N186AE accident near Jacksonville, Florida

Probable cause

The flight instructor's improper decision to attempt hover flight without hydraulic power and his subsequent loss of control.

NTSB analysis

The certified flight instructor and a commercial pilot receiving instruction were practicing maneuvers in the helicopter with the hydraulic system turned off, to simulate a hydraulic system failure. The commercial pilot was conducting a practice approach to a runway, with a transition to a hover. As the helicopter approached 5 feet above the ground, the commercial pilot began to lose directional control of the helicopter. The flight instructor assumed control; however, the helicopter entered multiple revolutions, climbs, and descents before it contacted the ground, spun, and rolled over. The fuselage, tail rotor and main rotor drive systems were substantially damaged. Examination of the helicopter did not reveal any preimpact mechanical malfunctions; nor did either pilot report any mechanical abnormalities. According to the helicopter manufacturer's flight manual training supplement, hovering without hydraulic power was not an approved procedure and would result in "excessive pilot workload, poor aircraft control, and possible loss of control."

Text from the NTSB. Open the NTSB docket for ERA09TA440 for the full record.