What happened
On July 28, 2004, at 17:25 local time, a Bell UH-1H helicopter, registration EC-GOD, was engaged in firefighting operations near El Berrocal, Huelva. The aircraft, operated by Helisur, was performing water-loading maneuvers at the El Tabladillo reservoir. At the time of the accident, two other helicopters were operating in the immediate vicinity.
While the aircraft was positioned near the water surface to utilize its ventral suction pump, it lost control and impacted the reservoir. The impact caused the aircraft to become partially submerged. During the event, the pilot attempted to manage the descent by adjusting the collective, but the main rotor blades also struck the water. The pilot managed to exit the submerged cabin through a breach in the upper cockpit area. Although the pilot was unable to swim, they reached the shore and were assisted by the crew of a nearby helicopter. The pilot sustained one injury involving a head laceration and a hand injury.
The investigation
The CIAIAC examined the wreckage of the EC-GOD after it was recovered from the reservoir. The inspection revealed significant structural damage, including a displaced main transmission, a broken main rotor mast, and a deformed left skid. Investigators found that the tail rotor shaft had suffered a torsional fracture at the point where it connects to the transmission.
Witness testimony from another pilot on-site indicated that the suction pump hit the water surface, causing the rear of the skids to dip into the water. The witness observed the aircraft's nose lift and the tail rotor blades entering the water, followed by a rapid rightward rotation and the eventual sinking of the aircraft.
Findings
- The investigation established that the pilot likely committed an error during the flare or the water-loading maneuver, causing the tail rotor to strike the water surface.
- The resistance created by the tail rotor blades hitting the water generated a torque that resulted in the torsional failure of the tail rotor shaft.
- The loss of anti-torque control caused the aircraft to yaw violently to the right, leading to a loss of control and the subsequent impact of the main rotor blades with the water.
- The pilot was not wearing a helmet or a life jacket at the time of the accident. The investigation noted that a helmet could have prevented the head injury, and a life jacket would have mitigated the drowning risk, especially as the pilot was not a swimmer.
Safety action
- REC 45/05: The CIAIAC recommended that the DGAC establish requirements for firefighting helicopter operations to ensure that crews carry life jackets when performing water-loading maneuvers over bodies of water.