Rotational Engine Balancing
 Rotational mass balance is another dimension of balance used by Victor technicians. This differs from reciprocating mass balance, as this is only the movement in the rotational direction as the engine propeller turns. This mass is made up of the crankshaft, counterweights, gears, and large end of the connecting rods, connecting rod bolts and nuts and factored for oil weight.
When engines are originally manufactured they are built using theoretical balance procedures. This assumes that when the parts are put into motion, that they will remain balanced. In real-time operation under load, the balance changes and effective balance takes over. Over a period of time, such imbalance could crack engine mounts, crankcases and exhaust systems, cause premature bearing failure and propeller overloads, result in increased engine temperatures and induce vibration in the cockpit.
Additionally, an engine imbalance can introduce harmonics in flight controls, instruments and airframe members and is one of the leading causes of premature engine wear. Balancing not only improves thrust but also reduces pilot and passenger fatigue by lowering the amplitude of various vibration frequencies generated by the engine.
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