Rotor balancing

Solutions to detect propeller/rotor unbalance.

Reduce vibration, minimise component fatigue and improve passenger comfort.

A practical choice for reducing wear and tear

An unbalanced rotor, when rotating, wants to revolve around its mass centre axis. Because the bearings restrict this movement, the centrifugal force, due to the unbalance, causes the rotor to vibrate. This vibration causes wear to the bearings, creates unnecessary noise, and, in extreme cases disintegration of the rotor itself can be experienced. It is therefore necessary to reduce the unbalance to an acceptable limit.

Our electronic products collect data and signals that are transmitted to the airborne avionics. Rotor unbalance detected data are then processed to support the maintenance operations on the aircraft.

Propeller balancing - enhancing passenger comfort and maintainability

The vibrations induced by propeller unbalance on a turboprop aircraft not only generate noise in the cabin, they can cause fatigue on bearings and a reduced time life of gearbox components.

To increase passenger comfort and improve durability, we have developed a propeller-balancing system. It is based on our latest AGILE new modular electronic processing unit.

The propeller-balancing system is comprised of:

  • One vibration monitoring computation unit (VMCU)
  • One single axis accelerometer per propeller
  • One GSS software running on standard PC

This monitoring system is designed to collect primarily the mechanical vibration signature from the propeller of each engine. Data and signals collected by the VMCU, including those provided directly by the aircraft avionics, will be acquired, processed and stored on-board, and whenever needed, transmitted to the airborne avionics or ground system equipment. The propeller unbalance data processed by the VMCU, as well as the balancing recommendation provided by the GSS, will then be used by customers to support the maintenance operations on the propeller.

Rotor trim and balance (RTB)

We design and manufacture high-end transducers systems for rotorcraft applications, which are qualified for engines and airframe vibration analysis. Our systems include piezoelectric accelerometers, cables and charge converters.

We also provide vibration analysis for helicopter engines and airframes with high temperature capability. Learn more about these using the links below.

Vibration sensors
Helicopter health and usage monitoring systems (HUMS)
Engine monitoring units (EMU)

Our electronic units are advanced computing platforms that are not only tailored to their primary function, but also comprise a segregated area where advanced diagnostic and prognostic algorithms can be implemented. The development and validation of such signal processing algorithms is either done by Meggitt's (RTB) helicopter rotor trim and balance system, aero engine fan trim balance functions) or supplied by the OEM in order to be implemented on the computing platform.

We can provide rotor trim balancing with our electronic units AGILE (the new modular solution), data acquisition and processing unit (DAPU) and vibration processing unit (eVPU) for helicopter and aircraft applications.

Cold fan trim balancing - saving on maintenance time and costs

We have introduced on-board fan trim balancing data acquisition and processing on our Engine Vibration Monitoring (EVM) units and Engine Monitoring Units (EMU) units, offering many advantages over existing equipment. These units having cold fan trim balance software built-in are bringing savings on maintenance time and costs.

Fundamental balancing procedure:

  • The amplitude and the angle of the unbalanced weight are measured and calculated. An equivalent weight is mounted 180° opposite the unbalance weight.
  • Data acquisition of unbalance vibration measurements, both amplitude and phase, occur during a revenue flight at multiple rpm values and under stable conditions. Stability criteria can be user-defined to increase acquisition probability.
  • Modeling algorithms use the unbalance vibration amplitude and phase to calculate the unbalance weight amplitude and angle. Influence coefficients characterising the engine are pre-loaded for each engine type, but the operator can modify specific coefficients.
  • The calculated counter-weight will be displayed on the front panel of the unit or via the MCDU (multi-function control and display unit), including the part number of the screw and location of the hole.

Features and benefits

  • Reduces vibration, minimises component fatigue and improves passenger comfort
  • Support and reduce maintenance operation costs on the aircraft
  • Increase passenger comfort and improve maintainability


Our rotor balancing systems are used on the following platforms:

  • Engine health monitoring (EMU) systems used for civil aircraft on new generation of engine-aircraft projects
  • Cold fan trim balancing used for civil aircraft, business jets and regional aircraft
  • Health monitoring on civil aircraft, regional aircraft, business jets and UAS
  • HUMS application for the helicopter market
  • AGILE (smart condition monitoring) can be used in practically all markets to expand monitoring functions to smaller assets (e.g. auxiliary power units, air cycle machines, generators and gearboxes)

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

Featured products