What happened
On 7 January 2019, an Airbus AS350 B3, registration F-GKMQ, was engaged in a slung load transportation mission near Le Galot, France. The operator, Airplus Hélicoptères, was tasked with positioning sections of a telecommunications tower using a sling system.
During the installation of the fourth tower section, the pilot was hovering over the structure to allow ground technicians to secure the load. While the load was being positioned, the helicopter suddenly lost altitude. This was immediately followed by a sharp increase in altitude as the pilot applied significant collective pitch. This rapid vertical movement caused the sling to go taut and subsequently jerk the tower section away from the structure.
Following the separation of the load, the helicopter entered an uncontrolled roll to the right. The aircraft struck trees before the left side of the fuselage collided with the ground. The impact resulted in one fatality (the pilot) and the destruction of the helicopter.
The investigation
The BEA examined flight data from the engine data recorder, the FADEC, and the VEMD, as well as video footage captured by a technician on the ground. The investigation also included an analysis of the aircraft's mechanical systems, the slinging equipment, and the pilot's medical history.
Investigators reviewed the sequence of flight parameters, which showed a distinct reduction in engine rating and altitude, followed by a rapid increase in pitch and altitude. The investigation also looked into the pilot's recent medical examinations and identified several cardiovascular risk factors, including high blood pressure and a high BMI. Additionally, the investigation examined the pilot's recent work stressors and his history of managing chronic back pain.
Findings
- The primary cause of the loss of altitude was a manual reduction of the collective pitch by the pilot, though the exact reason for this input—whether due to turbulence, an unexpected cockpit event, or a temporary loss of control—could not be definitively determined.
- The subsequent sudden increase in altitude caused the sling to snap the load away from the tower.
- The pilot's medical examination revealed significant cardiovascular risk factors, including obesity and hypertension, as well as evidence of underlying heart and liver issues that could have potentially led to a temporary incapacitation, such as dizziness or fainting.
- The pilot had been managing chronic sciatica, which may have impacted his ability to maintain the specific posture required for observing the load through the cockpit floor window.
- The pilot had deviated from established company procedures by performing the initial stages of the mission without a ground helper and without conducting a stabilized hover check.