Expected governor performance

I have an MT 3-blade prop and MT governor purchased about four years. I have seen several post about surging but my question has to do with slow changes in RPM.
I have noticed up to a -40 and +10 RPM change in RPM while in cruise. At first I thought this was in instrumentation problem but I have now been able to reproduce an issue where slightly moving the prop control will quickly bring the prop back to the requested RPM.


It almost appears like the governor gets off speed and sticks until I change the control setting.


The plane is just out of phase 1 with about 50 hrs total time. My current thoughts are a possible restriction in the governor filter screen causing the initial RPM change due to oil starvation. I am also concerned about the fly weights in the governor not moving freely through their range.


Any thoughts from the CS guys?

Hi JD,
It could be any of the issues you have mentioned. I would recommend sending this in for a bench check to establish if the governor is running wrong. The other option would be to put a new gasket on. I sell them for around $18.00 and may be the cheaper way to troubleshoot. I think you are in Cali, if so American Propeller do a good job with governors and would probably give you a good turn around time.

Good Luck!

Don't rule out the control cable itself. You might be seeing effects of some lost motion somewhere in the cable or its mounting. See if you can move the gov lever by finger pressure with the cable connected. When reviewing cable routing, take into account that the engine moves forward slightly due to the thrust load.

I'm kinda with them on checking the cable and mounting brackets first, sounds like an odd failure mode for the gov.

There are a couple of more local governor shops as well. My favorite is Truespeed at VNY airport.