Governor. MT v Hartzell?

[Finley Atherton]

Just replaced my MT P-860-4 with the HZ 320/360 from Vans (Hartzell p/n S-1-10). One difference I found is that the Hartzell governor will not make the Hartzell prop go to coarse pitch at idle power whereas the prop would go coarse with the MT even with the engine producing no power (windmilling, ignition off and mixture at idle cutoff).

I liked this feature of the MT as going coarse significantly increases the glide if the engine fails but is still windmilling.

I replaced the MT as it was due for it's 6 year overhaul (the Hartzell has no calendar TBO) as this would save money in the long run but I am now seriously considering getting the MT overhauled and reinstalling it.
Thoughts, comments??

Fin
9A
Australia

[Chkaharyer99]

Didn't know that about the fine/course pitch, MT vs Hartzell. Are you sure about that?

You got a warranty with that new Hartzell.

[Finley Atherton]

Originally Posted by Chkaharyer99

Didn't know that about the fine/course pitch, MT vs Hartzell. Are you sure about that?

If I recall correctly from a thread years ago some were surprised that the prop would go coarse at idle power as the accepted wisdom was that there is insufficient oil pressure/rpm at idle for the governor to control the prop to coarse. So I suspect the Hartzell governor is working correctly but it does not have the oil output to control the prop at idle power (the prop stays fine even with the blue knob full out)

Fin.

[Bavafa]

Interesting...I am in the same boat and really considering going with Hartzell if I am to send mine for overhaul. I believe the cost of overhaul is $800 which seem pretty high compare to what they are new and their track record for handing this SB seem very poor.

Have you contacted Hartzell to see if this is normal?

[Finley Atherton]

Originally Posted by Bavafa

Have you contacted Hartzell to see if this is normal?

I have not contacted Hartzell. The governor is otherwise performing as expected so I suspect this is normal for this governor with my Hartzell prop.

Fin.

[Dustyone]

With the new RV-14 here at Redcliffe, I noticed the same thing, it really needed above 1700 rpm to get the prop to cycle whereas the Mt Govenor on my RV-10 will cycle at much lower RPMs.

Now if I could only get my Govenor back from the Prop Shop where they are still awaiting parts for the SB31 .........

[Avengerboss]

You are correct about Hartzell needing a minimum of 1800 to work, I just learned that myself when I thought my Govenor was bad and I called Hartzell and that's what they stated. I really like mine now , works great and like you said no TBO .

[BobTurner]

My Hartzell governor, bought from Vans, will cycle at a 1700 RPM runup.

[scsmith]

Well, now I'm rethinking my strategy here......I just bought a Hartzell but haven't opened the box yet. Being able to get to course pitch on a windmilling prop might make a big difference in the outcome of an engine failure. Maybe it does make more sense to get the MT rebuilt.

[BillL]

Originally Posted by Finley Atherton

If I recall correctly from a thread years ago some were surprised that the prop would go coarse at idle power as the accepted wisdom was that there is insufficient oil pressure/rpm at idle for the governor to control the prop to coarse. So I suspect the Hartzell governor is working correctly but it does not have the oil output to control the prop at idle power (the prop stays fine even with the blue knob full out)

Fin.

I don't think it is pressure, as the oil pressure needed for full pitch is less than 15psi. I used air for doing this. Likely, it is the flyweights don't have sufficient force to overcome the counter balance spring. That would be by design.

Edit. Hartzell may have a different combination of springs that will allow a lower speed control. They should be consulted for that.

Edit II. I clearly did not understand what I was talking about here. Each governor has a built in pump to provide oil pressure boost. How low the rpm can be and still get full pitch is related to aerodynamic forces on the prop. I currently can not get below 2300 rpm at full power with my S-1-10 hartzell at 8000 ft, but if I go to idle rpm or to ICO, and pull the gov control, I can consistently get around 1300 rpm. Soooo, it is pressure but depends on the torque on the blade. hope this helps someone.