What happened
On 22 June 2009, an Eurocopter AS 350 B3, registration EC-IOJ, was engaged in firefighting operations near Mollet del Vallés, Spain. The aircraft, operated by TAF Helicopters, S.L., was utilizing a specialized belly tank system to collect water from a pond to combat nearby forest fires.
During the third or fourth refilling operation, the helicopter began to climb after taking on water. As the aircraft ascended, a rope attached to the suction pump—which was intended to keep the pump submerged—remained connected to a post on the pond's perimeter fence. As the helicopter moved away, the rope was pulled taut and eventually snapped. The sudden release caused the rope to whip upward into the main rotor system. The rope, along with a heavy stone used as a weight and the suction pump assembly itself, became entangled in the blades. The impact of these objects caused the severe fracture of two main rotor blades, leading to an immediate loss of control and a parabolic descent into the ground. The impact resulted in 2 fatalities and the total destruction of the aircraft.
The investigation
The CIAIAC examined the wreckage, including the remains of the suction pump, the broken rotor blades, and the recovered rope. Investigators analyzed the flight path and the configuration of the Simplex Fire Attack System. The investigation also reviewed the maintenance records, the pilot's credentials, and the operational procedures for the firefighting mission. Physical evidence, such as paint transfers on the blades and the position of the suction pump components, helped reconstruct the sequence of events where the rope's tension led to the mechanical failure of the rotor system.