DYNAMIC PROP BALANCING
What are the benefits of a dynamically balanced propeller?
Dynamically balanced propellers increase ride quality and component service life. Both contribute greatly to safety. Pilots report that vibration-induced fatigue on long flights was significantly reduced following a prop balance. Many of the vibrations you accepted as normal will be gone. And because of this reduced vibration, the service life of components is extended. My prop was balanced at overhaul. Isn’t that good enough? While all propellers are statically balanced at overhaul, static balance is performed on the propeller alone. Dynamic balance is concerned with the entire rotating assembly (engine and propeller) in its normal operating configuration. The result is a true running balance under all operating conditions. How is dynamic balance done on the aircraft?
Nothing is removed from the propeller or engine. A small sensor (Velocimeter) like that shown in the photo below is mounted near the propeller to measure the motion produced by an out-of-balance condition. The sensor signal is processed by the balancer in conjunction with the hand-held Strobex. The resulting information indicates the required correction to attain a balance. The basic principle is similar to balancing the wheels on a n automobile. Can all props be dynamically balanced? All propellers can be dynamically balanced as long as the have provisions for distribution of balance weights. Dynamic balance has been applied to propellers ranging in size from ultralights to C-130s. It is not possible to balance propellers having internal mechanical problems or excessive out-of-track blades. How long will a dynamically balanced prop stay in
balance?
In normal use, propeller dynamic balance should be checked every 400-600 hours or after prop engine overhaul. If significant repairs are made to the propeller, dynamic balance should be rechecked.
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