On 9 December 2012, the pilot of a Robinson R44 Raven I helicopter, registered VH-WOH, was conducting aerial spraying activities on a property near Mudgee, New South Wales. Following the completion of a number of spray runs, the helicopter failed to return to the refilling station, and a search was commenced. The helicopter was found about 450 m up a hill from the refilling station, having collided steeply with terrain. The pilot was fatally injured.
What the ATSB found
Analysis of the recovered global positioning system data identified that immediately before the accident the helicopter was climbing up a hill when the speed decreased below about 10 kt (19 km/h). The ATSB found that at the time of the accident the helicopter was over its maximum allowable weight, was too heavy to hover out-of-ground effect and as the speed decreased, the power required exceeded that available from the engine resulting in a probable reduction in main rotor RPM (overpitch) and a descent. The time between this point and the first contact with a tree was insufficient for the pilot to complete a recovery action. The ATSB also found that the spray system on the helicopter had not been installed by an approved aircraft maintenance engineer.
This accident highlights the dangers of operating helicopters overweight, especially when performance is critical, such as when low flying or conducting aerial spraying operations. The use of manufacturer’s performance data will assist pilots in avoiding the circumstances associated with this accident.