Difference between Hartzell and McCauley CSU

[Steve888]

I'm trying to work out what the main differences are between Hartzell and McCauley CSU props.

So far as I can work out, the governing system is the same, but the differences lie in which direction the oil pressure acts to move the propeller and therefore which way the prop will move in a governor failure.

Can anyone enlighten?

[Always Moving]

I do not think there is much differences.

In a twin if you loose pressure the prop should go to almost feather (low RPM)

In a single if you loose pressure the prop should go to fine pitch (high RPM)

The reason for the the twin is obvious, for the single I guess they want you to still have the option of starting the engine since it is the only one you have.

In the other hand, the twin will not totally feather unless you move the prop to feather BEFORE it reaches the minimum RPM. And putting a full feathering system in a single would cost more money.

[Air Tourer]

In my Ag-wagon, the McCauley went to fine in a dive with the throttle full back, but the Hartzel went course. One tended to over rev on throttle up, the other made a horrible noise while getting back to climb pitch.