This paper proposes a diagnostic technique that can predict component degradation for a number of complex systems. It improves and clarifies the capabilities of a previously proposed diagnostic approach, by identifying the degradation severity of the examined components, and uses a 3D Principal Component Analysis approach to provide an explanation for the observed diagnostic accuracy. The diagnostic results are then used, in a systematic way, to influence maintenance decisions. Having been developed for the Auxiliary Power Unit (APU), the flexibility and power of the diagnostic methodology is shown by applying it to a completely new system, the Environmental Control System (ECS). A major conclusion of this work is that the proposed diagnostic approach is able to correctly predict the health state of two aircraft systems, and potentially many more, even in cases where different fault combinations result in similar fault patterns. Based on the engineering simulation approach verified here, a diagnostic methodology suitable from aircraft conception to retirement is proposed.

本文提出了一种诊断技术，可以预测许多复杂系统的组件退化。它通过识别被检查组件的退化严重程度来改进和阐明先前提出的诊断方法的能力，并使用 3D 主成分分析方法为观察到的诊断准确性提供解释。然后以系统的方式使用诊断结果来影响维护决策。该诊断方法是为辅助动力装置 (APU) 开发的，通过将其应用于全新系统环境控制系统 (ECS) 来显示其灵活性和强大功能。这项工作的一个主要结论是，所提出的诊断方法能够正确预测两个飞机系统的健康状态，并且可能更多，即使在不同故障组合导致类似故障模式的情况下。基于此处验证的工程仿真方法，提出了一种适用于从飞机概念到退役的诊断方法。