AS332L2 Super Puma, G-PUMS, 29 July 2011
AS332L2 Super Puma, G-PUMS
Summary:
The helicopter was cruising in IMC at an altitude of 3,000 feet when the No 2 Automatic Flight Control System (AFCS) disengaged. The pilots reset the No 2 system but, shortly afterwards, the No 1 system disengaged. The pilots reset the No 1 system but, almost immediately afterwards, both systems disengaged, the helicopter yawed significantly to the right and full left yaw pedal input was required to regain balanced flight. The pilots were unable to re-engage either of the AFCS channels and so elected to descend to find VMC below cloud. Once in VMC, the pilots turned the helicopter towards Aberdeen Airport. They were able to reset the AFCS after approximately 10 minutes and the aircraft landed without further incident.
The operator commented that this was the first such occurrence in over 7 years of their operating this equipment. The manufacturer found independent failures in the two AFCS computers: a pin was broken on a circuit board within one computer; and the 15 V supply voltage was out of range from a circuit board within the other computer.
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