Forced landing due to retreating blade stall, says ATSB
On 15 July, the Australian Transport Safety Bureau (ATSB) issued its final report into the forced landing of a rescue helicopter that took place at Port Pirie Aerodrome in February 2013.
On 15 July, the Australian Transport Safety Bureau (ATSB) issued its final report into the forced landing of a rescue helicopter that took place at Port Pirie Aerodrome in February 2013. The crew of the helicopter were conducting a trauma recovery flight. After reaching cruise altitude, the crew observed fluctuations of the hydraulic system pressure gauges. Shortly after, the helicopter sustained an inadvertent and violent nose-up pitch and rolled left before descending. The pilot regained control at about 800 ft above ground level and flew back to the aerodrome.
The ATSB did not find any mechanical or system faults that could account for the hydraulic system pressure fluctuations, but did find that the helicopter was being operated ‘at a weight, density altitude and airspeed, and in meteorological conditions that were conducive to the onset of retreating blade stall’.
Since the incident occurred, the operator has advised its pilots of the conditions conducive to retreating blade stall and the correct actions to recover from that condition, said the ATSB.