A health and usage monitoring system for detecting an anomalous condition indicated by the sensed vibrations on an aircraft, comprising: a first, vibration, sensor (105, 115) configured for performing signal processing on sensed data, a central control module, and a communication network connecting the first sensor and the central control module, wherein the first sensor comprises: a signal processing circuit configured for local signal processing, software configured for executing on said signal processing circuit, said first sensor (105, 115) configured for sensing vibrations in at least one axis of motion, a communications device configured for transmitting data to and receiving data from a remote location on the aircraft, and a mount, wherein the first sensor (105, 115) is configured to be mounted near a first component on the aircraft and for monitoring the operation of the first component, wherein the software is configured for analyzing the vibrations sensed by the first sensor (105, 115) and for local determination of when an anomalous condition is indicated by the sensed vibrations, characterised by said remote location including a second, rotational speed, sensor the second sensor being mounted near a second component on the aircraft, wherein data received from the second sensor is configured to be used by the software to configure the operation of the first sensor (105, 115), and data received from the second sensor comprises a digital representation of a rotation speed of the second component on the aircraft, and the digital representation is configured to be used to derive key system frequencies which the first sensor will be configured to monitor. a first, vibration, sensor (105, 115) configured for performing signal processing on sensed data, a central control module, and a communication network connecting the first sensor and the central control module, wherein the first sensor comprises: a signal processing circuit configured for local signal processing, software configured for executing on said signal processing circuit, said first sensor (105, 115) configured for sensing vibrations in at least one axis of motion, a communications device configured for transmitting data to and receiving data from a remote location on the aircraft, and a mount, wherein the first sensor (105, 115) is configured to be mounted near a first component on the aircraft and for monitoring the operation of the first component, wherein the software is configured for analyzing the vibrations sensed by the first sensor (105, 115) and for local determination of when an anomalous condition is indicated by the sensed vibrations, characterised by said remote location including a second, rotational speed, sensor the second sensor being mounted near a second component on the aircraft, wherein data received from the second sensor is configured to be used by the software to configure the operation of the first sensor (105, 115), and data received from the second sensor comprises a digital representation of a rotation speed of the second component on the aircraft, and the digital representation is configured to be used to derive key system frequencies which the first sensor will be configured to monitor.