NTSB Identification: ANC12LA017
14 CFR Part 91: General Aviation
Accident occurred Sunday, January 15, 2012 in Fairbanks, AK
Probable Cause Approval Date: 01/30/2014
Aircraft: PZL-SWIDNIK SW-4, registration: SP-SSW
Injuries: 3 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

During a hover test above the departure end of the runway, the flight test technician turned the hydraulics system off to simulate an in-flight hydraulic failure. During a series of prearranged hover maneuvers, the pilot began to hover the helicopter to the left, at which time, the cyclic and collective became very "stiff and ratchety," which was followed by a forward and left movement of the cyclic that the pilot was unable to physically overcome. The helicopter subsequently descended, the left skid struck the runway, and the helicopter rolled onto its left side, which resulted in substantial damage to the fuselage, tail boom, and main rotor drive system. A postaccident examination revealed no evidence of any preimpact mechanical anomalies that would have precluded normal operation.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A loss of control during a simulated hydraulic emergency, which resulted in an inadvertent dynamic rollover from the which the pilot could not recover.

Full narrative available

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