Two Pilots Reportedly Took Off With Yaw Servo Hydraulic Switches In The 'Off' Position

Airbus has issued a safety information notice for several models of AS350 helicopters equipped with dual hydraulic systems.

The notice indicates that the pilots of two AS350 series helicopters may have taken off with the aircraft's yaw servo hydraulic switch in the "off" position. While the safety notice does not identify the specific events, it does indicate that they are being looked into by "the applicable governmental investigative authority."

According to a report appearing in Vertical Magazine, taking off with that switch set to "off" results in a complete lack of hydraulic boost to the tail rotor system, but does not trigger an annunciator of any kind in the cockpit. The increased load on the yaw pedals could be interpreted as a tail rotor failure by the pilot.

The purpose of the safety information notice is to remind pilots of AS350 B3, AS550 C3, and AS355/AS555 models equipped with dual hydraulics of the procedures and indications for the run-up hydraulic checks in these aircraft, and of the importance of strict compliance with the pre-takeoff checklist.

FMI: www.airbushelicopters.com