This paper provides guidelines and procedures to optimize the ABIT BIT failure rate design of built-in-test (BIT) during the conceptual phase of system design. M maintenance man-hours per flight hour Optimization of the BIT design is achieved by properly specifying three Ma mean administrative delay time key design parameters: BIT effectiveness, mean corrective maintenance M ii mean corrective maintenance time time, and BIT reliability. These parameters together with the BIT design-MDt mean operational downtime per maintenance acto-cost target form the baseline criteria for designing the BIT equipment To n during subsequent phases. The paper provides straightforward tion mathematical tools, sensitivity analyses, and tradeoff procedures. MDT" mean operational downtime per malfunction M 1 mean logistics delay time