Method and apparatus for detecting oscillatory phenomena indicative of

Abstract

A method and apparatus for detecting oscillatory phenomena indicative of airflow separation or sensor common mode oscillatory failure is disclosed. The oscillations of a differential pressure transducer that senses the pressure difference on the opposite sides of an airfoil are bandpass filtered to remove oscillations lying outside of a band of interest. Oscillation peaks lying within the passband that exceed a positive or negative threshold produce pulses that are counted. The counter value is decremented each time an alternating peak is not detected within one-half cycle of a minimum frequency. If the allowable count threshold is exceeded, a latch is set. Setting the latch produces a command that can be used to inhibit the operation of systems that rely on data produced by the differential pressure transducer. An alternative path senses the position of a control element (e.g., rudder pedal position) and sets the latch if the control element position reaches an extreme value likely to produce an oscillation condition at the pressure differential transducer. The latch is reset if the oscillation condition subsides for a predetermined period of time. This provides protection against transient conditions without inhibiting control system operation for the balance of a flight.