Review of maintainability design principles and their application to conceptual design

The life cycle cost of a system is, to a large extent, influenced by its maintainability. Besides being a statistical concept, maintainability is a design parameter whose achievement is influenced by known elements and attributes. However, these elements and attributes appear far and wide in literary sources. This paper consolidates these elements and attributes by reconciling and developing previous research efforts. It also shows how these attributes interact with each other to influence major maintainability indices such as mean time to repair (MTTR), maintenance policy, and others. It is also further argued that the conventional tendency of 'handpicking' certain attributes to assess maintainability is to a great extent ad hoc, and it is shown how it could be rationalized. Finally, it is observed that the number and diversity of these requirements makes their assessment during conceptual design impossible because of 'cognitive overload'. Therefore, an approach to maintainability analysis during conceptual design, based on the concept of functional design and maintainability axioms, is proposed.