Health and usage monitoring (HUMS)

HUMS processes and analyses the complete suite of vibration and helicopter data. It also helps to trend, diagnose and predict the health of helicopter systems.

Helping increase reliability and availability, and reduce costs

A typical HUMS has three main airborne tasks: cockpit voice recording; flight data recording and the ground task of maintenance data analysis.

HUMS is a helicopter health and usage monitoring system designed to sense the vibration of the main reduction and accessory gearboxes, main and tail rotor, and engines.

The HUMS system designed by Meggitt is a monitoring system that primarily senses the vibrations of the reduction and accessory gearboxes, acquires and processes signals from the sensors, and reports monitored system faults. It also helps to diagnose the most critical components of the helicopter.

Meggitt helicopter HUMS have been in service for over two decades. Meggitt has in operation and in development a wide range of on-board HUMS electronic units, a complete range of sensors related to vibration health monitoring (VHM) of helicopters and ground station software (GSS).


How HUMS can work for you

Your maintenance data is analysed to:

  • Detect incipient defects in major components before they can hazard the safety of flight
  • Detect the exceedance of a range of limitations
  • Increase reliability of many items of equipment by minimising airframe vibration.

A longer term goal, from the analysis of data over a long period, is to base component replacements more on the ground of condition and usage than simply on hours-in-service, thus reducing unnecessary maintenance costs. This concept is called Condition-Based Maintenance (CBM).

What HUMS includes

For each helicopter, HUMS typically comprises an on-board electronic unit, usually referred to as data acquisition and processing unit (DAPU), multiple accelerometers, remote charge converters (RCC) and associated cables, rotor speed and position sensors, a pilot interface panel (PIP) or a control and display unit (CDU) and the GSS.

The on-board DAPU at the heart of the HUMS

The DAPU receives data from cockpit instrumentation, accelerometers, speed and position sensors. It enables you to achieve all this:

  • Main and tail rotor vibration monitoring and balancing (RTB)
  • Main and tail gearbox and tail drive shafts vibration monitoring
  • Bearings vibration monitoring
  • Oil cooler shaft vibration monitoring
  • Engine vibration monitoring during steady-state and transient phases
  • Acquisition of raw data from a specific sensor
  • Cockpit microphone recording
  • Communication management

The DAPU continuously monitors flight data available and checks it against both event and exceedance equations.

Key accelerometers

Our accelerometers are mounted on the main gearbox so that each accelerometer can monitor several shafts within the gearbox. Sophisticated software in the GSS enables you to monitor the health of individual gears and bearings. Accelerometers are also mounted on the tail rotor drive gearboxes, and on the airframe at various points. The tail-rotor has usually one accelerometer mounted with its axis along a radial of the tail rotor disc, to monitor balance, and another along the axis of rotation, to monitor aerodynamic loads.

Most engines have two higher temperature piezoelectric accelerometers.

Features and benefits

  • Vibration processing units (VPU) and enhanced vibration processing units (eVPU) perform signal conditioning, data acquisition and processing sensors for diagnostics
  • Generic vibration processing units (gVPU) with their own power supply that does not have to be mounted in the HUMS rack as VPU
  • Dynamic monitoring acquisition units (DMAU) process and store relevant data to monitor the helicopter’s usage, assess its health to optimise its maintenance schedule and the tuning of the main and tail rotors by tracking various data and providing information that will be used for RTB purpose.
  • Acquisition of flight data recorder (FDR) and cockpit voice recorder (CVR) data (can be integrated in the combined CVFDR)
  • GSS can be installed on a notebook, stand-alone computer or computer network
  • Typical data acquisition and processing units (DAPU) feature:
    • Vibration signal (IEPE) acquisition interface: 46 channels
    • Azimuth tachometer signal acquisition interface: 9 channels
    • Rotor blade tracker signal acquisition interface: 2 channels
    • Rotor blade tracker excitation power supply interface: 1 power output channel.
  • Plan preventative maintenance, enhance quality and safety and reduce costs of helicopter operation
  • Light HUMS can be based on the AGILE family of units providing 8, 16 and 24 monitoring channels depending on the specific requirements of the helicopter application.


  • Airframe structure vibration analysis
  • Gearbox analysis
  • Bearing analysis
  • Rotor trim and balance
  • Usage

At Meggitt, we can provide you with a sensing and monitoring solution that is specific to your aerospace application and can be further customised to your particular requirements. To discuss what you need in more detail, please contact us.

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