Abstract: In one embodiment, a method is provided for detecting a fault condition in a drivetrain, including the steps of monitoring torque oscillations at a location along a drivetrain, and detecting at least one fault condition associated with a drivetrain component by evaluating torque oscillation data acquired during the monitoring. In another embodiment, a system is provided for detecting a fault condition in a drivetrain including a torque sensor coupled to a drivetrain component and configured to measure torque at a location along the drivetrain and to generate a torque oscillation signal corresponding to the measured torque, and a controller configured to receive the torque oscillation signal and evaluate the torque oscillation signal to identify at least one fault condition associated with the drivetrain component.

Abstract: One embodiment of the present application is a gas turbine engine with a compressor that includes a variable geometry mechanism to vary working fluid flow area. A desired state of this mechanism is selected different than a current state to change the amount of flow area. The mechanism has a hysteresis band corresponding to a difference between increasing the flow area to reach the desired state and decreasing the flow area to reach the desired state. To control operation of the mechanism within this hysteresis band, a determination is made whether the desired state corresponds to a greater flow area or a lesser flow area relative to the current state.