Abstract: An ice detection system, in particular to a system for detecting icing conditions and a system for detecting the presence of ice formed on a structure, and the methods for doing the same. Two heaters of the ice protection system (experiencing substantially the same environmental conditions) are driven to different temperatures (the first greater than or equal to 0° C., and the second less than 0° C.). The difference in the powers required to drive the two heaters indicates the prevailing environmental conditions. A heater of the ice protection system is driven and the rate of change of surface temperature is measured over several periods. A substantial deviation from a rate of change of surface temperature, which indicates the presence of ice on the surface of the structure, is detected.

Abstract: An oscillatory servo-valve fault monitor is provided for identifying faults attributable to servo-control system components. In particular, both low frequency and high frequency (oscillatory) fault responses are identified. Such oscillatory fault responses are distinguished from normal position control adjustments and transient responses. As the reaction to a fault condition is to shut down the faulty actuator and corresponding servo-control, such capability avoids inadvertent shut-downs. Independent detection paths are provided for sensing low frequency responses and high frequency responses. Each path includes a respective window comparator and up-down counter. For a given path, the window comparator defines two thresholds--in effect, a window. If the monitored signal amplitude is outside the window, then a counter or count signal is incremented. If the signal amplitude is within the window, then the counter or count signal is decremented.

Abstract: A reconfigurable fixture for holding a plurality of workpieces in proper position for manufacturing. The fixture includes an array of interleaved uniformly spaced contoured headers, with a predetermined set of headers corresponding to a predetermined workpiece contour. Each set of contoured headers may be simultaneously laterally displaced from an inactive stored position to a locked, active forward position, wherein the selection and movement of the set of headers is controlled by a computer controller. Each contoured header has a set of vacuum cups, that, when activated, pulls the predetermined workpiece against the contoured edges of the predetermined set of headers.