What happened
On January 21, 2016, at approximately 4:30 p.m., an Eurocopter AS-350B helicopter, registration HI-850, was performing a landing at a grassy area near La Leonor de Toma, Santiago Rodríguez, Dominican Republic. The aircraft had departed from the former Cibao Airport in Santiago de los Caballeros with a pilot and three passengers on board.
During the landing sequence, the aircraft touched down on an irregular surface. As the helicopter attempted to transition back into a hover to find a more suitable landing spot, the right skid became caught on the terrain. This created a pivot point that caused the aircraft to tilt sharply to the right, leading to a dynamic rollover. The impact of the main rotor blades with the ground caused severe damage to the aircraft, including one rotor blade breaking off and striking a nearby house.
All four occupants (the pilot and three passengers) escaped the wreckage uninjured.
The investigation
The CIAA investigation examined the terrain, the aircraft's maintenance records, and the pilot's flight experience. Investigators analyzed video footage provided by witnesses, which showed the landing site had a lateral slope exceeding the limits specified in the aircraft's flight manual. The investigation also reviewed the pilot's credentials, noting that this was his first unsupervised commercial operation in this specific helicopter model following his training.
Findings
- The landing site was a grassy plain with a lateral slope of approximately 10 degrees, which exceeded the maximum allowable inclination for the Eurocopter AS-350B as defined in the manufacturer's flight manual.
- The uniform color of the grass may have made it difficult for the pilot to perceive the true slope of the terrain during the approach.
- The pilot failed to adhere to the manufacturer's operational parameters regarding terrain inclination.
- The pilot's attempt to re-establish a hover after the initial touchdown was executed with an inadequate configuration, contributing to the rotor imbalance.
- The dynamic rollover was triggered when the right skid became fixed to the ground, acting as a pivot point during the maneuver.