Incident Overview
During the landing sequence, the aircraft was on short final approach at an indicated airspeed between 120 and 125 knots. The crew extended the flaps to the full down position. As the flaps reached the fully extended configuration, the stall warning horn activated and the stick pusher mechanism of the Rosemont Stall Avoidance System engaged.
Crew Actions
The captain promptly disengaged the Stability Augmentation System (SAS) clutch. The approach continued without further incident, and a normal landing was executed. The stall warning horn remained audible until touchdown.
Post-Event Investigation
Following the event, maintenance personnel conducted a calibration check and bench test of the stall warning and avoidance system components. The testing did not identify any anomalies or reveal the reason for the unexpected activation. The root cause of the malfunction could not be determined from the available diagnostic procedures.
Technical Details
The aircraft was configured with full flaps for landing. The Rosemont Stall Avoidance System is designed to provide aural and tactile warnings to prevent inadvertent stalls. The specific conditions leading to the activation during normal flap extension at the reported airspeed remain unexplained.