What happened
On February 6, 2016, an EC 1/20B helicopter, registration SE-JLZ, operated by Jämtlandsflyg, was performing aerial wildlife management duties in Dalarna county, Sweden. During the mission, the crew attempted to land on a narrow, snow-covered road situated within a dense forest area near Lövnäsvallen.
To maximize the distance between the tail rotor and nearby obstacles, the pilot maneuvered the aircraft to position the rear of the helicopter toward the largest available clearances. While hovering over the landing site, the rotor blades made contact with the tops of two trees on the right side of the aircraft. The impact resulted in substantial damage to all three rotor blades, including delamination and a broken edge on one blade. The damage was not discovered until the engine had been shut down following the landing. No injuries were reported, and no damage occurred to any property other than the aircraft and the trees.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the landing site, the aircraft's technical condition, and the crew's operational procedures. The investigation focused on the suitability of the chosen landing site and the pilot's ability to maintain required clearances.
Investigators noted that the pilot was operating from the left seat to better coordinate with the assistant, who was also seated on the left. While the pilot had received specific training for this configuration, the investigation considered how this position might have affected spatial perception. The investigation also reviewed the company's operations manual, which requires a minimum distance of three meters from the rotor tip to any fixed obstacle during occasional landings. For this aircraft, which has a 10-meter rotor diameter, this necessitates a minimum 8-meter clearance from the rotor center to any obstacle.
Findings
- The primary cause of the accident was that the landing site did not undergo sufficient reconnaissance prior to the landing and touchdown.
- The chosen landing site was too narrow to allow the pilot to maintain the required safety margins; the shortest distance from the rotor center to the nearest obstacles was only 5.3 meters.
- The pilot's use of the left-hand seat may have contributed to an incorrect perception of the distance to the obstacles on the right side of the aircraft.
- The impact was localized to the rear parts of the blade tips, where the tree tops were severed by the metal-clad front edges of the blades.