Model-based selection of accelerometer locations for helicopter gearbox monitoring

A novel method is introduced to quantify, based on the structure of the gea rbox, the monitoring effectiveness of accelerometer locations on the housin g. In this method, monitoring effectiveness of sets of accelerometer locati ons is defined in terms of two indices: the coverage index and the overlap index. The coverage index is obtained from an influence matrix defining the level of effect of component faults on accelerometer readings. The overlap index denotes the level of overlap between pairs of accelerometers in cove rage of components. The effectiveness of the proposed method is verified ex perimentally based on measurement-fault data obtained from an OH-58A main r otor gearbox. The estimated rankings of various sets of accelerometer locat ions based on the estimated values of their monitoring effectiveness agree closely with those obtained empirically.