Check the pop control cable at the governor end. I recently encounter similar prop control issues and discovered that the metal sleeve on the prop control cable had separated permitting the cable to flex. It took several close inspections to discover the problem ? reach in and try moving he sleeve because it looked attached but wasn?t.
I have checked, but always worth checking again.
Just had a long discussion with hartzell on something similar. Did you take off the top off the governor? If so, you have to be precise in how you hook the spring back on during reassembly. They happened to mention that they had recently got a call from a guy with the same symptoms. They ultimately found that was off by one flat on the spring clocking when he reassembled his governor.
That top plate isn't supposed to come off for lever clocking. Only the screws get loosened to rotate the cover, then re tightened.
Hartzell tells me that governor should control down to 1600 or so.
Larry
Larry, I have been talking to the H guy for a week. I checked the clocking and it was off. I changed it and it is not the issue. It did help by 100 rpm though indicating it is not the prop. Now H is asking for a static RPM check. I did not do one when the engine was installed due to break-in concerns, but shall do it today and report results. That will only test the low pitch setting and high pitch is internal, so the request does not seem to be directly related to the issue.
The photo below shows the changed clocking found.(photo below) I am pretty sure I did not do it, but it did not solve the issue anyway. Yes, they tell me 1700 too, but no joy on that.
My frustration is that no definitive diagnosis seems to be employed, just some guesses and me doing the work. It is a new governor (18hrs) via Vans.
After I do the static rpm check the governor is coming off. Maybe I can find some gasket issue, but H thinks not.
Behavior is like this: 8000'DA, WOT, Rich, dial down the speed until it stops and add one full turn on the vernier, about 2300/2310. Then dial back mixture (engine torque), as FF/torque is reduced the rpm drops and just before stumbling, it is around 2160-2180 RPM.
A few things could be wrong (my theory)
1. the pressure output from the governor is too low thus unable to overcome aerodynamic forces to give more pitch from the prop. (prop blade loading is higher for lower rpm at same airspeed)
1.A. The pressure could be low due to high leakage in prop supply circuit.
1.A.1 The supply circuit leakage is high due to a) high engine leakage, or b) internal leakage from gov, c) restricted oil flow to gov (gasket or debris)
2. Prop high pitch stop is wrong ( factory setting) and it is hitting the high pitch stop.
#2 unlikely ( in my brain) because it changed with the clocking exercise.
Actions Summary- static rpm test, governor removal for shipment (somewhere) to be tested. Bill is
not happy.