What happened
On December 14, 2017, an Airbus Helicopters AS 350 B3, registration LN-OPA, was conducting a cargo operation at Brettesnes in Lofoten, Norway. The mission involved transporting materials for concrete work. Prior to the incident, the crew had been performing longline operations, moving a concrete block and other equipment near the landing site.
As the pilot was completing the final approach to a pier, an orange bigbag (a large fiber cargo bag) containing various items, including a 60-liter drum and longline equipment, was caught by the helicopter's downwash. The bag was lifted into the air and struck the main rotor. The impact caused intense vibrations that lasted for several seconds, continuing even after the aircraft had touched down and the engine was at idle. The pilot quickly shut down the engine and exited the aircraft to safety. There were no injuries to the crew or ground personnel.
The investigation
The Norwegian Safety Investigation Authority (NSIA) examined the landing site, the cargo bag, and the aircraft's operational procedures. The investigation focused on why the orange bag was able to become airborne despite the presence of other secured items nearby. Investigators also reviewed the operator's manual, which requires landing sites to be tidy and for loose objects to be secured or removed to prevent them from being blown by downwash.
Findings
- The primary cause of the accident was that the landing site was not sufficiently secured.
- The downwash from the descending helicopter provided enough lift to catch the filled orange bag, emptying its contents and lofting the bag itself.
- A southern wind of approximately 10-15 knots likely assisted in pushing the bag toward the helicopter's flight path.
- While other items near the aircraft remained stationary because they were heavy or tightly folded, the weight of the contents in the orange bag was insufficient to resist the rotor's aerodynamic forces.
- The impact with the rotor caused significant structural damage to the main rotor and the fuselage, ultimately resulting in the aircraft being declared a total loss.
Safety action
Following the accident, the operator, Helitrans AS, implemented an immediate safety measure prohibiting the placement of bigbags outside the aircraft unless they are positioned at a safe distance beyond the reach of rotor downwash. This prohibition extends to all known lightweight objects capable of being caught by the wind.