Abstract: A method comprising: receiving data from a first equipment health monitoring system, the data being for a plurality of parameters of a propulsion system; determining whether the data received from the first equipment health monitoring system includes data for a first parameter of the propulsion system; and instructing deployment of a second equipment health monitoring system to monitor the first parameter where it is determined that the data received from the first equipment health monitoring system does not include data for the first parameter.

Abstract: Apparatus comprising: a propulsion system; a first equipment health monitoring system configured to generate data for a plurality of parameters of the propulsion system; a second equipment health monitoring system configured to generate data for one or more parameters of the propulsion system, at least one of the one or more parameters to be monitored by the second equipment health monitoring system being different to the plurality of parameters to be monitored by the first equipment health monitoring system.

Abstract: A rotor assembly for a gas turbine engine. The rotor assembly comprising: a rotor comprising a plurality of rotor blades, wherein the rotor is arranged to rotate about an axis of rotation; a sensor arranged to measure a rotational signal indicative of the rotational speed of the rotor at a measurement point on the rotor; and a processor in communication with the sensor. The processor is arranged to receive the rotational signal and derive a rotor impact signal based on an offset in the measured rotational speed of the rotor at the measurement point. The rotor has an axial length (L) parallel to the axis of rotation, and the sensing apparatus is arranged to measure the rotational speed of the rotor at a measurement point along the axial length of the rotor, the measurement point corresponding to a position at or near an antinode of a torsional oscillation of the rotor resulting from an impact event.