What happened
On 30 July 1996, a SA 315B Lama, registration G-BNNF, was performing routine aerial forestry fertilization in the Knockalough forest block, Upperchurch, Co. Tipperary. The operation involved a coordinated effort between the pilot and a ground crew using specialized equipment to distribute fertilizer from underslung hoppers.
During the mission, the pilot attempted to load fertilizer into the hopper, but the equipment failed to function due to electrical issues. After two unsuccessful attempts to spread the load, the pilot returned to the dump site to allow the ground crew to replace the electrical leads. While the pilot maintained a low hover to facilitate the reconnection of the aircraft's hook and the third set of electrical leads, the aircraft drifted slightly. During this movement, the rear of the left skid made contact with the "A" frame handle of the hopper. As the pilot attempted to lift the aircraft, the skid became entangled with the frame. The pilot reached the limit of the starboard cyclic control, causing the helicopter to roll sharply to the port side and impact the ground under power. The entire sequence occurred in approximately three to four seconds, resulting in the aircraft being damaged beyond economic repair, though there were no injuries to the pilot or the ground crew.
The investigation
The investigation examined the mechanical state of the aircraft, the operational procedures, and the communication methods used between the pilot and the ground crew. The aircraft was found to have been properly maintained, and investigators found no evidence of technical malfunctions or adverse weather conditions contributing to the crash. The investigation also looked into the communication protocols used during the hooking-up phase of the operation.