Aerospace Power Supply Modules Reliability Estimation Using ARINC Reliability Apportionment Technique

Abstract

Reliability assures the proper functioning of the system for specified period. Development of a new system design requires certain specifications to be fulfilled to achieve the target reliability. Reliability Apportionment technique is a useful tool to achieve the target reliability by assigning the reliability to be met by each of the subsystems by consideration of risk involved, development cost and time. Reliability Apportionment helps in determining the weakest subsystem and guides the designer to focus on this subsystem to improve the reliability. The simplest reliability apportionment technique is equal apportionment which assigns equal reliability to all the subsystems. But equal apportionment assigns the reliability without consideration of risk involved in the development of each subsystem. Hence, reliability apportionment technique has to be selected which apportions the reliability to the subsystems based on the configuration, mission time and risk involved in development. In this paper, ARINC reliability apportionment technique has been adopted in assigning the reliability goals for the modules of aerospace power supply. Power supply consists of modules connected in series, components having constant failure rate, and the system follows exponential failure distribution which makes ARINC method suitable for apportionment. In ARINC method, weighting factor is calculated based on the failure rate predicted, which indicates the weakest card of the system and guides the designer to focus on that card for improvement of reliability.