Schweizer 269C-1 N61482 accident near Hillsboro, Oregon

Probable cause

The flight instructor's improper decision to take off from a hover with low rotor rpm.

NTSB analysis

While conducting a series of off-airport landings, the pilot receiving instruction circled the area and initiated a second approach to the predetermined landing area. During the approach and hover, the flight instructor observed the engine and rotor rpms at the bottom of the green arc and advised the pilot to bring the engine rpm back to the top of the green arc. The pilot informed the flight instructor that they were at full throttle, and the flight instructor took control of the helicopter. After hovering for about 30 seconds, the flight instructor performed a left turn and initiated takeoff. As the helicopter transitioned through effective translational lift, the flight instructor observed the engine and rotor rpms drop further, and the helicopter began to descend. The flight instructor maneuvered the helicopter toward a level road; however, the helicopter landed on sloping terrain and the tail rotor struck the ground. Postaccident examination of the helicopter revealed no mechanical malfunctions or failures that would have precluded normal operation. The engine was subsequently successfully started and run, with no anomalies noted. It is likely that if the instructor had landed the helicopter after taking control from the pilot receiving instruction, he would have been able to increase the engine and rotor rpms back to the top of the green arc and then make a successful takeoff.

Text from the NTSB. Open the NTSB docket for WPR12LA212 for the full record.