There really isn't much use for it in the sim, as the left and right engines are always perfectly matched.  In real life, it is almost impossible to have two engines run exactly the same, so you get slight variations in power and rpms from side to side.  The prop sync adjusts the rpms to match them, and to prevent the annoying noise from out of sync props.  Usually the prop sync is used once established in cruise.

DaveSims wrote on Jan 10^th, 2010 at 5:33pm:


Actually, this is not exactly correct. I fly the Cessna 414AW in real life and the prop sync is often a rather confusing device. Heres how it really works.

The prop sync, contrary to common belief, does not actually synchronize the RPMs. It syncs the physical position of the propeller blades. The easiest way to explain this is to actually think of the prop sync as unsynchronizing the position of the blades. The objective of this being to align them in such a way where a left engine prop blade is never passing the cabin when a right engine prop blade is. By arranging the blades in such a manner so no two blades are ever passing the cabin at the same time, you get a quieter cabin. The prop sync will effectively reduce noise even if the RPMs are split.

It is normally turned on after takeoff at the beginning of the climb, and is turned off as part of the final descent checklist.

Hope this helps.

Joe