What happened
On June 26, 2001, at approximately 07:00 local time, a EUROCOPTER AS-350-B3, registration F-OHCU, departed from the Ripollés Base near Queralbs, Spain. The flight was operating under Visual Flight Rules (VFR) to transport personnel and equipment to a construction site intended to protect a rack railway line from rockfalls in the Nuria Gorge.
The mission required the helicopter to land on a narrow, steep mountain ledge, measuring less than two meters in width. During the operation, the helicopter touched the ground with one skid to allow the first occupant and equipment to disembark. Following this disembarkation, the tips of the main rotor blades struck the adjacent rock face. The impact caused the aircraft to lose control and strike the slope, subsequently triggering a fire that destroyed the airframe.
The accident resulted in three fatalities among the crew and passengers remaining on board. One occupant, who had already disembarked, survived the incident without physical injury.
The investigation
Investigators examined the wreckage, which was scattered across a 200-meter radius, and analyzed data from the aircraft's Vehicle and Engine Multifunction Display (VEMD). The VEMD recorded an overtorque of 140%, the maximum measurable value, indicating a massive mechanical shock consistent with the rotor blades striking the rocks.
The investigation also reviewed the operator's manual and flight planning procedures. It was established that the pilot, who was not the regular operator for this specific route, was unfamiliar with the landing zone. Furthermore, the investigation looked into the coordination between the crew and the passengers, noting that a pre-flight briefing had not been conducted as required by the company's operations manual.
Findings
- The primary cause of the accident was the loss of control of the aircraft due to the impact of the main rotor with the rocks of the mountain during the disembarkation process.
- The selected landing area was insufficient, as its width did not meet the operator's requirement for a minimum 4x4 meter helisurface.
- There was a significant lack of coordination between the pilot and the occupants. This was driven by inadequate flight planning, the pilot's lack of familiarity with the specific terrain, and communication barriers caused by language differences between the French pilot and the Spanish-speaking occupants.
- The pilot's need to check the safety of the disembarking passenger likely caused a head movement that led to an unintended cyclic control input, bringing the blades into contact with the terrain.