What happened
On August 4, 2013, an Airbus Helicopters AS-350-B3, registration EC-KIE, was engaged in firefighting operations near Puebla del Maestre, Spain. After performing several water drops, the pilot returned to a base to refuel and rest. Upon receiving orders to check for a fire reflash, the pilot returned to the fire area and landed on a section of an old road to allow a ground squad to prepare the Bambi bucket for deployment.
While the crew was preparing the equipment, the aircraft began to bounce with increasing intensity. A firefighter, who was positioned underneath the nose of the aircraft to check the bucket latch, grabbed the right skid to steady himself. Fearing for the worker's safety, the pilot applied collective pitch to lift the aircraft. This sudden movement, combined with the weight of the worker hanging from the skid, caused the aircraft to destabilize. During the ensuing struggle to maintain control, the tail rotor struck the edge of a nearby road incline, causing the rotor to detach and the aircraft to lose all control. The helicopter eventually overturned on its right side, resulting in significant damage to the landing gear, main rotor, and tail components. The firefighter sustained minor injuries from flying debris.
The investigation
The CIAIAC examined the aircraft's maintenance records, the flight controls, and the physical wreckage at the site. Investigators analyzed the terrain, noting that the landing area was narrow and the ground surface was uneven. The investigation also reviewed the pilot's flight controls, finding that the friction settings for both the cyclic and collective levers were set to their minimum. The investigation included technical assistance from the aircraft manufacturer and the French BEA to inspect the main rotor head, gearbox, and anti-torque system.
Findings
- The primary cause of the accident was a failure to comply with landing procedures, which led to the helicopter becoming unstable while on the ground.
- The destabilization was likely triggered by the uneven ground surface and involuntary movements of the flight controls.
- The reduced dimensions of the landing area limited the pilot's ability to maneuver safely.
- The friction settings on the cyclic and collective controls were at their minimum, which likely led to the pilot overcorrecting during the emergency.
- The firefighter's decision to hold onto the right skid introduced variable loads that further hampered aircraft stability.
- The detachment of the anti-torque rotor was caused by its impact with the edge of the road incline.