Prognostic health management for avionic systems

Maintenance of aircraft electronic systems has traditionally been performed in reaction to reported failures or through periodic system replacements. Recent changes in weapons platform acquisition and support requirements have spurred interest in application of prognostic health management (PHM) concepts developed for mechanical systems to electronic systems. The approach, development, and validation of prognostics for two types of electronic equipment are discussed in this paper. The two applications, a switch-mode power supply and a GPS receiver were selected based on their relatively high failure rates and relevance to many commonly used avionics systems. The method identifies prognostic features by performing device, circuit, and system-level modeling. Device modeling with equivalent circuit and mathematical physics of failure models describe parameter degradation resulting from damage accumulation for each device. Prognostic features extracted from a small array of sensors on the power supply, and from the GPS operational communication data stream are used to update life usage and failure progression models to provide an indication of the health state. The results of accelerated failure tests on both systems are used to illustrate the approach and demonstrate its effectiveness in predicting the useful life remaining. The solutions have applicability to power supplies in many avionic systems, and to a broad class of mixed digital/analog circuitry including radar and software defined radio.