On-line diagnostics of a variable displacement pump of a flight actuation system

An on-line diagnostic system for a variable displacement pump, serving as a part of a self-contained flight actuator, is presented. A mathematical model describing dynamics of the pump, driving a control surface of an aircraft, is established. Typical pump failures are defined through the model parameters in the form of a failure pattern library. A diagnostic model, intentionally sensitive to particular failures, is defined. A diagnostic procedure, featuring on-line parameter estimation of the mathematical model, failure detection and identification is developed. A failure prediction procedure, detecting and utilizing trends exhibited by parameter estimates is formulated. The results are verified by computer simulation.