Precision ...

It's all about how we do the measurement - almost all prop shops and prop balancers will use a single accelerometer to survey your vibration. We prefer to ALWAYS use two - that way we can see what's going on at the back of your engine in response to our balancing weights on the front. This is really important in order to arrive at the lowest possible vibration in your aircraft and to provide a full vibration survey report to you.

We must use two sensors to distinguish the propeller from the crankshaft since both of these components turn at the same rpm and the only way to tell one from the other is to use two sensors.  If we balanced a propeller down to a .05 IPS using the front transducer and at the rear of the engine, the sensor is reading a .6 or .7, the culprit is really the crankshaft. This would never be discovered if we used a single sensor.

In a situation like this, where we reach a very low reading at the front only to discover a high value at the rear we re-balance using both sensors to reach a compromise value, where the front and rear readings are made equal. The pilot will still notice a very significant reduction in vibration in the cockpit and the engine will experience a lower torsional vibration throughout.

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