Fluid leakage prediction for civil aircraft hydraulic systems by fusing physics-informed and parameter momentum

Due to its high frequency, sneaky nature, and possible safety hazards, hydraulic fluid leakage in civil aircraft systems necessitates fault prognostics technology to enable condition-based maintenance for early identification and avoidance. However, leakage fault prognostics faces challenges such as limited monitoring parameters, coarse granularity of onboard alerts, and discontinuity in fluid quantity data caused by pre-flight servicing. In order to estimate the likelihood of leakage occurring, this research suggests a time-series model that combines physics data with fluid amount momentum. The model first introduces physical constraints such as the fluid’s coefficient of thermal expansion and the manual-specified allowable leakage rate. Furthermore, by distinguishing between intra-flight and inter-flight modes, a parameter momentum indicator for fluid quantity is constructed to capture the cumulative trend interrupted by servicing and refueling. Finally, a time-series model is utilized to map the dynamics of the fluid quantity, enabling accurate prediction of early and minor leakages. Leveraging real-world operational data from a domestically produced commercial aircraft, this case study validates the proposed method’s capability to effectively predict the probability of incipient leakage. The approach offers valuable decision support for implementing condition-based maintenance and advancing the health management of the hydraulic system.