Setting HUMS condition indicator thresholds by modeling aircraft and torque band variance

Health and usage management systems (HUMS) compute a number of condition indicators (CIs) from physical measurements, such as vibration. These CIs are used to characterize the health of the component. When the CI exceeds some threshold, the component is deemed to be in warning (perform additional analysis) or alarm (component is faulted and requires maintenance). This work presents an approach for the robust configuration of thresholds to control false alarm while maintaining reliable detection. Results are presented for this methodology applied to the CIs monitoring a typical helicopter drive train.