Fairbanks, AK, USA
SP-SSW
PZL-SWIDNIK SW-4
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.
On January 15, 2012, about 1423 Alaska standard time (AST), a Polish registered PZL Swidnik SW-4 helicopter, SP-SSW, sustained substantial damage when it collided with terrain, following a loss of control while maneuvering at the Fairbanks International Airport, Fairbanks, Alaska. The Polish production test pilot and two flight test technicians on board were not injured. The helicopter was operated by PZL Swidnik S.A., Swidnik, Poland, as a 14 CFR Part 91 visual flight rules (VFR) test flight when the accident occurred. Visual meteorological conditions (VMC) prevailed at the Fairbanks Airport. The local area flight originated at the Fairbanks International Airport about 1315, and company flight following procedures were in effect. During a telephone interview with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on January 19, the on-site flight test manager for PZL Swidnik reported that the accident helicopter was undergoing cold weather flight testing at the time of the accident. He said that after the helicopter departed from the Fairbanks International Airport, the flight test crew flew a series of preplanned flight test maneuvers to the southeast of the airport. After completing the one hour flight, the crew returned to the Fairbanks International Airport to begin a series of hover tests, with the helicopter's hydraulic systems disabled, to simulate an in-flight hydraulics failure. The flight test manager said that as the pilot hovered the helicopter above the departure end of Runway 2L, the flight test technician turned the hydraulics system off to begin the simulation. As part of the prearranged flight test plan, the pilot hovered the helicopter sideways, first to the right and then to the left. He said that as the pilot began to hover the helicopter to the left, the cyclic and collective became very stiff and ratchety, followed by a forward and left movement of the cyclic, which the pilot was unable to physically overcome. The helicopter subsequently descended, the left skid struck the runway, and the helicopter rolled to the left, with the main rotor blades striking the runway. As the main rotor blades struck the runway, the helicopter continued to roll onto its left side, sustaining substantial damage to the fuselage, tail boom and main rotor drive system. The closest weather reporting facility was the Fairbanks International Airport, Fairbanks. At 1432, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind, calm; visibility, 6 statute miles with ice fog; clouds and sky condition, 500 feet few, 1,100 feet broken, 2,500 feet broken; temperature, minus 36 degrees F; dew point, missing; altimeter, 31.05 inHg. After the accident, the helicopter was returned to the manufacturer's production facility in Poland. According to the production flight test manager's written statement included in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the manufacturer, there were no mechanical anomalies discovered during the postaccident examination of the helicopter that would have precluded normal operation.
A loss of control during a simulated hydraulic emergency, which resulted in an inadvertent dynamic rollover from the which the pilot could not recover.
Source: NTSB Aviation Accident Database
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