What aircraft was involved and where did it happen?

The accident on 2005-09-02 involved a aircraft, registration OH-HLP, at FI.

What was the probable cause of the accident?

The pilot's inadequate understanding of aerodynamics and handling characteristics prevented the recognition and correction of a loss of tail rotor effectiveness caused by specific flight conditions, including low speed and tailwind.

Helicopter Loss of Control Leads to Water Impact in Paltamo

A Bell 206B helicopter crashed into a water hazard during a filming flight in Finland due to a loss of tail rotor effectiveness.

What happened

On September 2, 2005, at approximately 13:30, a Bell 206B helicopter, registration OH-HLP, crashed into a water hazard at the Metelinniemi golf course in Paltamo. The aircraft, operated by First Invest Oy, was performing an aerial photography mission to film the golf course for a presentation video.

The helicopter was flying at an altitude of 150–200 feet above ground level, following the edge of a fairway at speeds between 20 and 30 knots. As the pilot approached the end of a course segment, the aircraft's nose began to yaw unexpectedly to the right. Despite attempts to regain control, the rightward rotation accelerated, and the helicopter spun approximately 1.5 to 3.5 times around its vertical axis. The aircraft then struck the water with its landing gear, tilted left, and the main rotor impacted the water surface before striking the left side of the fuselage. The impact caused the helicopter to capsize upside down. All three occupants managed to escape the submerged aircraft on their own.

The investigation

The investigation examined the flight conditions, the pilot's training, and the aircraft's maintenance history. Investigators established that the aircraft was experiencing a loss of tail rotor effectiveness (LTE). The investigation also revealed significant maintenance discrepancies, including a missed 3,000-hour inspection of the tail rotor drive shaft, which was overdue by approximately 2,065 hours. Furthermore, the pilot's training was found to be insufficient regarding the recognition and recovery of LTE-related flight states.

Findings

The primary cause of the accident was the pilot's lack of knowledge regarding the helicopter's aerodynamic handling characteristics and flight properties.
The loss of control was triggered by a loss of tail rotor effectiveness caused by a combination of low airspeed, a left sideslip, a right turn, a relatively high aircraft weight, and a tailwind.
The pilot failed to recognize the onset of the uncontrolled rotation and was unable to implement corrective actions.
Contributing factors included the pilot's limited experience with aerial photography and the presence of a tailwind.
Maintenance failures were identified, specifically the failure to perform a required tail rotor shaft inspection and discrepancies in the aircraft's maintenance logs.