A simulation framework for the prediction of the dynamic behaviour of a jet engine internal air system

Modern safety-critical systems increasingly rely on fault tolerant control, condition monitoring, and maintenance strategies to manage progressive degradation while maintaining safe operation. Capturing the combined effect of these mechanisms requires modelling approaches that move beyond static reliability representations and explicitly account for dynamic interactions between physics, control, and maintenance. This study presents a Petri Net-based simulation framework for modelling component degradation, system control behaviour, and maintenance actions within a single, unified architecture. The framework enables physical system behaviour and reliability logic to interact dynamically over time, allowing their joint evolution to be captured without reliance on external model coupling. The framework is demonstrated through application to a jet engine internal air system, where multiple degradation mechanisms, control dependencies, and inspection policies act simultaneously over an engine operating interval. Simulation results illustrate how system-level safety and degradation emerge from these interactions, highlighting the influence of control logic and maintenance timing on fault escalation. Together, these results demonstrate how the proposed framework can be used to analyse dynamic safety and reliability behaviour arising from the interaction of degradation, control, and maintenance in complex safety-critical systems.