Using Degradation Messages to Predict Hydraulic System Failures in a Commercial Aircraft

This paper presents a failure prognostics methodology based on degradation messages using a particle filter framework. In the proposed method, the degradation messages are interpreted as quantized measurements. The use of degradation messages reduces the need for data communication bandwidth, since they only need to be transmitted or stored when some predefined threshold is crossed. In contrast, the direct monitoring of degradation-related measurements requires frequent updates, usually at a fixed sampling rate. This characteristic is fundamental on failure prognostics applications in real aircraft due to the high infrastructure costs associated with data transmission. A case study using field data recorded from commercial aircraft is presented to illustrate the proposed methodology. The problem under consideration consists of estimating the time remaining until the fluid level reaches unacceptably low values in the hydraulic system. Two quantization steps are considered in the evaluation. Predictions employing direct measurements of fluid level are also performed to establish a comparative performance baseline. The results show that it is possible to choose a quantization step that allows a reduction in the transmission costs without significant loss of prognostics performance.