| 摘要 |
Built-in test equipment (BITE) of the electrical/electronic systems of an aircraft is provided in-part by passive fault detection circuitry that is integrated into the electrical/electronic systems for continuous, in flight monitoring of line replaceable units (LRUs), such as temperature and pressure sensors. Both steady and intermittent failures of the LRU components are detected, and the type and location of each failure are identified and stored in a memory for continuous display or for subsequent recall by ground maintenance crews. The primary feature of the disclosed circuitry is its ability to detect and distinguish between an open impedance fault of a critical LRU component and an open wiring fault in the interconnect wiring that is associated with each component and is needed to electrically communicate signals developed at remotely mounted sensor components with a centralized controller, usually located in the avionics bay. To enable such differentiation between these two most frequent kinds of faults, each system component that is to be monitored is provided with one or more shunts having predetermined impedance relationships with the associated component so that an open component failure, when detected through the interconnect wiring, appears as a measurably different electrical condition than an open failure of the interconnected wiring which leads to that component. The capability of distinguishing between open component and open wiring faults minimizes the frequency at which LRUs incorporating critical components are simply replaced, without remedying the malfunction.
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