Accident Overview
On March 14, 2017, at approximately 10:59 Japan Standard Time, a Eurocopter AS350 B3, registered JA500H, operated by Hirata Gakuen, suffered a rollover accident at Kobe Airport. The helicopter was conducting annual pilot training at the time. The two occupants, a pilot in command (PIC) and a pilot undergoing annual training, were not injured. The helicopter was destroyed but did not catch fire.
Flight History
The helicopter departed Kobe Airport at 10:04 for annual training. After completing various training maneuvers, including continuous takeoffs, landings, and autorotation training, the crew initiated hydraulic system failure training around 10:35. The PIC, seated in the left seat, directed the training pilot in the right seat to simulate a hydraulic failure using the ACCU TST push button. The training pilot set the Hydraulic Cut Off switch to OFF as per emergency procedures. The helicopter conducted a running landing on a grass area within the airport's landing area.
Transfer of Control and Accident Sequence
Immediately after the running landing, before the helicopter came to a complete stop, the PIC announced 'I'm taking over' and assumed control. The PIC intended to restore hydraulic pressure and return to the apron quickly. While the PIC operated the Hydraulic Cut Off switch to ON, the collective pitch lever rose. The helicopter began to rotate left and then rolled over to the right. Both pilots reported feeling that the right rear skid was caught on something. The helicopter came to rest on its right side.
Probable Causes
The Japan Transport Safety Board determined that the accident occurred because, during the transfer of control after a running landing in hydraulic failure training, left rotation developed and the helicopter experienced dynamic rollover. The right skid became stuck in the ground, serving as a fulcrum for the rollover. The left rotation likely resulted from the collective pitch lever rising after control transfer without appropriate corrective input. Contributing factors included simultaneous hydraulic pressure restoration and inadequate holding of the collective pitch lever.
Investigation Notes
The investigation was conducted by the Japan Transport Safety Board, with participation from representatives of France as the state of design and manufacture. The on-site investigation, interviews, and airframe examination took place in March and April 2017. The engine data recorder was analyzed. No injuries were reported, and the helicopter was destroyed.