Smooth running machines last longer and with operator fatigue. Considering the cost of aircraft engines, making them operate smoothly even more important to extend engine life and performance.
An aircraft’s propeller is essential a giant flywheel bolted right to the output shaft of most single engine piston aircraft. With this “direct drive” approach, the engine and propeller are essentially one integrates unit. If the prop is out of balance, then the engine is out of balance.
The prop manufacturer statically balances the prop, meaning the prop is balanced, but only with itself. Likewise engine manufacturers balance engines to various degrees of refinement.
So why doesn’t a balanced prop mated to a balanced engine not actually balanced? The balance points of each is slightly different. And it’s this difference that causes vibration.
The remedy is to have the prop dynamically balanced. Dynamic balancing is accomplished by adding very small amounts of weight in the form of a washer tactically mounted to the prop’s mounting flange.
A special sensor is attached to a prop blade and as the prop spins, the out of balance rotation is detected by a computer program that suggests where to place the counter balance weights on the prop hub.
The proof not just in the data, but the feel of the plane. Other seasoned pilots are astonished how smooth the engine operates.
A quality dynamic prop balance costs between $200-$350 depending shop rate and part of the country. Many shops charge a flat fee to perform the service. Worth EVERY penny.