propeller synchrophasing/synchronizing

The maintenance of correct phase difference between adjacent propellers of a multiengine aircraft throughout the normal flight range. This phase difference results in what is known as propeller beat noise. Synchronizing the propeller RPM reduces the interference noise caused by interaction between the blades of adjacent propellers to the minimum.

Synchrophasing allows the pilot to adjust the phase angle between the propeller on the various engines to reduce the noise and keep vibration to a minimum.