AMETEK AEROSPACE Products has introduced a system to give fast, accurate propeller balancing, allowing regional-turboprop operators to keep down damaging vibration levels throughout an aircraft's life.

The Balance Monitoring System automatically stores vibration data in flight. These data are then downloaded to a ground-based lap-top computer which calculates the balance weights and locations required. The US company says that because of the speed and ease of the system, which eliminates the need for ground runs, propellers can be regularly rebalanced, cutting vibration levels and increasing airframe and component life.

The system, which can be factory-installed or retrofitted, can store data from more than 100 flights.

Propeller rebalancing is traditionally carried out only once a pilot has reported excessive vibration. Ametek says that field data from a regional-aircraft manufacturer show that propellers commonly operate at vibration levels at least two or three times above normal limits before rebalancing.

"This means the aircraft typically are operating between 50% and 80% of their flight time with vibrations which are above the limits set by the manufacturer," the company says. A permanently installed monitoring system allows propeller re-balancing to be performed "within minutes" and allows vibration to be kept at a low level.

Accelerometers on each of the propeller-reduction gearboxes are connected to a central balance-monitoring unit which is used to calculate the vibration spectrum of each propeller.

Source: Flight International