Abstract: Analysis and control of a new aircraft’s direct maintenance cost (DMC) in preliminary design is an important procedure. It can help reducing the aircraft’s life cycle cost and enhancing its competence in the market. But today, methods for DMC estimating have low accuracy and need much knowledge of experts. This article proposes a method for DMC estimating by using Case-based Reasoning (CBR). Through experiences, this method need less knowledge and has more than ten percent higher accuracy than other methods.

Key words: aircraft design, maintenance cost, case-based reasoning, maintainability, economic, similarity