Minimizing Total Lifecycle Expected Costs of Digital Avionics’ Maintenance

Continuous growth in modern avionics systems complexity allows the extension of the functionality of flight control and navigation systems and leads to an increase in operating expenses. Currently, avionics maintenance costs approximately 30% of the total aircraft maintenance costs. Great impact on the avionics maintenance cost has high rate of intermittent failures, which has been estimated as approximately 50% in military avionics. Here, a mathematical reliability model of continuously tested LRU subject to permanent and intermittent failures is developed. Mathematical expressions for availability of redundant systems are derived considering the spare part system sufficiency. A detailed analysis of the three different variants of the breakdown maintenance strategy (BMS) of modern avionics systems is presented. A criterion of optimizing the number of spare parts is proposed. Some considerations for choosing the optimum variant of the BMS are outlined.