The Effect of Imperfect Maintenance on a System's Condition considering Human Factors

Abstract

Human Factors (HF) have a significant impact on the maintenance quality and are recognized as a specific cause of Imperfect Maintenance (IM). Technician inexperience, poor procedure uality, or environmental factors are exemplary HF and can lead to insufficient repair or inspection. However, due to limited data, many studies describe HF only qualitatively as a possible cause of IM or highly simplify the effect of HF. This paper attempts to analyze the effect of HF on the system’s restoration level in order to provide a more realistic post-maintenance operating system condition. Furthermore, the economic savings potential of a fully automated condition-monitoring approach and the subsequent reduction of adversarial HF within the maintenance process will be analyzed. As use case serves the tire pressure maintenance task of an Airbus A320. Based on fuzzy logic, an IM model is developed, considering the effect of HF individually on restoration and inspection tasks using human reliability assessments. The aircraft maintenance eco-system is simulated with a prescriptive maintenance model to enable the evaluation of monetary and non-monetary performance indicators. A comparative study revealed that perfect maintenance approaches tend to vastly underestimate the maintenance-related cost aspects. Moreover, the study showed that a technician’s lack of experience cannot be compensated by an improved working environment. Only the use of an automated monitoring system to replace error-prone inspection tasks resulted in an overall cost reduction. The developed model allows the individual evaluation of the technician’s expected performance to enable a more targeted deployment of the available workforce and to improve the effectiveness of maintenance.