Abstract: A system for measuring clearance between a stationary object and a movable object is provided. The system includes at least one sensor configured to be disposed on the stationary object and configured to measure an operating parameter corresponding to the movable object and a controller coupled to the at least one sensor, wherein the controller is configured to control an operating mode of the sensor based upon the measured operating parameter.

Abstract: A method for sensing and reacting to jet engine fan speed in excess of a fan speed computed from an aircraft throttle input is disclosed. Engine fan speeds are detected by adding test conditions to a main central processing unit (CPU) and adding test conditions to an independent overspeed module to provide additional protection from main CPU computational errors. Interpretation of sensor data relating to engine speed may initiate a modeling routine for sensor data. Comparison of measured/computed sensor data to desired conditions using logic and data tables is a used. If an anomaly is detected, engine fuel cutback devices are engaged.