Accident with the helicopter SE-JVM at Långtora airfield

Summary

The purpose of the flight was to carry out an inspection of power lines. The flight was the second of the day and it was preceded by a refuelling stop at Enköping/Långtora Airport. The crew consisted of a pilot and a system operator. The helicopter was parked on a grassy area outside a hangar with its nose towards the east. The take-off weight was 2,811 lbs. The weather at the location was clear and sunny, with a south-westerly wind.

After the engine was started, the helicopter hovered up to just above ground level. In connec­tion with the hover, the helicopter began to rotate clockwise. The pilot was unable to stop the rotation despite using full pedal travel. The helicopter rotated while rising to a height of approximately 15 metres before descending during rotation and hitting the ground. The crew got out of the helicopter with the help of witnesses who were at the scene. Those on board suffered minor injuries.

Rescue services, police, ambulance and an ambulance helicopter were called to the scene. Both crew members were taken to hospital for examination and treatment.

No unusual sounds, warnings or malfunctions were perceived by the crew before the rotation began. The pilot has also stated that he perceived the wind to be coming from the front during take-off and hover.

The technical investigations conducted have not identified any faults that could have contributed to the accident.

Causes of the accident

During take-off, the helicopter operated at high power output and a relatively high take-off weight. The relative wind was coming from the rear on the right side, which contributed to the helicopter's fin acting like a weather vane. These conditions likely exceeded the tail rotor's thrust capacity, resulting in an unanticipated right yaw that developed into an uncon­trolled rotation.

Contributing factors:

The pilot's perception that the wind was coming from the front likely contributed to the yaw being unexpected.

Safety recommendations

None.