Eurocopter AS350B3 Ecureuil crash near Góis, Portugal

An instructor and pilot were practising bucket work near Góis, the day before the fire season opened, when the helicopter began rotating left during the transition from the hover with a full Bambi bucket. The instructor could not stop the rotation with pedal and reported unusual control forces. After turning through about 360 degrees in a descent, the bucket dragged through vegetation and the helicopter pitched down and crashed. Investigators found the hydraulic cut-off switch had been activated inadvertently at very low speed, that incorrect wiring from an unverified service bulletin allowed all hydraulic assistance to be lost, and that three of four hydraulic accumulators were incorrectly preloaded.