Hughes 369A (OH-6A) N501SU accident near Palmer, Alaska

Probable cause

A partial loss of engine power after take off for an undetermined reason, which resulted in a hard landing.

NTSB analysis

The pilot was departing on a local flight in a turbine-powered helicopter. During the initial climb, about 35 feet above the ground, the engine lost power. The pilot entered an autorotation and attempted to cushion the landing, but the helicopter landed hard and the main rotor blades struck the tail boom, severing it from the helicopter. After the accident the engine continued to run, but at low power, requiring the pilot to close the engine throttle and shutdown the engine. A Federal Aviation Administration (FAA) postaccident examination revealed no preaccident mechanical anomalies with the engine or helicopter. The engine was removed from the helicopter, shipped to an engine service center, and placed in an engine test cell. At the direction of an FAA airworthiness inspector, and assisted by an air safety investigator from the engine manufacturer, the engine produced power that was within the manufacturer's performance standards.

Text from the NTSB. Open the NTSB docket for ANC09LA110 for the full record.