Contents I. Introduction
Many industrial systems and consuming products contain balanced components, for example, the wheels of trains and the multiple propellers of unmanned aerial vehicles (UAVs). Unlike conventional multicomponent systems, such systems and products generally require a balanced performance provided by each component to fulfill their intended missions. The analyses regarding the reliability and availability of balanced systems have attracted considerable attentions in both the communities of researchers and practitioners [1]. However, extensive review of literature reveals that how to optimize the maintenance policies for balanced systems has been underexplored. For practitioners in reliability engineering, the precise understanding of system reliability is mostly employed to advise decision making problems in order to cut operational cost and improve the system performance. Among these problems, maintenance policy optimization has been a pivotal one, which acts as a long-lasting popular topic in related research areas [2]–[4]. As sensor technologies advance at an immense pace in recent decades, condition-based maintenance (CBM) that utilizes the system health information, which is usually modeled as degradation, to advise maintenance scheduling is playing an increasingly important role to achieve appealing maintenance outcomes at lower costs [5]. The failures of components in many balanced systems can be attributed to degradation, in which case the CBM policy can be applied.
