What happened
On the evening of September 17, 2009, a Bell 47 G2 helicopter, registered F-BOFU, was engaged in aerial spraying operations at an agricultural research center in Saint-Andiol, France. The pilot was tasked with spraying cleaning products and rinsing water over greenhouses located approximately 50 meters from the takeoff area.
Following a refueling and replenishment stop, the pilot prepared for the final mission of the day. The intent was to complete the spraying and return to base before nightfall. To reach the greenhouses, the pilot followed a standard departure path, flying at an altitude lower than the surrounding obstacles, which included an 8-meter hangar and 3-meter shrubs.
During the climb, despite utilizing maximum available power, the helicopter failed to gain sufficient altitude to clear an obstacle in the flight path. The aircraft collided with a 3-meter-tall piece of agricultural machinery located directly in the takeoff axis, eventually coming to rest inside a greenhouse. The aircraft was destroyed in the impact.
The investigation
The investigation focused on the aircraft's performance and the accuracy of the weight and balance data used by the pilot. Examination of the wreckage confirmed that the engine was delivering power to the main rotor at the moment of impact.
Investigators discovered significant discrepancies regarding the aircraft's actual takeoff mass. The weight and balance documentation provided by the operator was outdated, dating back to November 2006, and failed to account for recent equipment modifications or the specific configuration of the spraying kit. Furthermore, there were conflicting reports regarding the weight of the spraying kit: the pilot and operator estimated it at 30 kg, the flight manual supplement suggested 60 kg, but post-accident weighing revealed the actual mass of the kit was 78 kg.
Findings
- The primary cause of the accident was the pilot's lack of knowledge regarding the actual takeoff mass of the aircraft.
- The aircraft was heavier than anticipated, which prevented the pilot from clearing the agricultural machinery during the climb.
- The operator failed to provide up-to-date documentation, as the weight and balance sheet did not reflect the current equipment configuration.
- Inconsistent information regarding the mass of the spraying kit contributed to the error in weight calculation.