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Lowest Governed RPM?

BillL

Well Known Member
I am about half way through phase I and found that the my Hartzell prop gov won't regulate the speed lower than 2400 rpm. What do the other governors (for the 360-M1B) have for a lower limit? This seems a bit high.
 
During your runup, when you cycle the prop do you get an rpm drop? If so, it is likely not the governor but the high pitch stops in the prop.
 
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During your runup, when you cycle the prop do you get an rpm drop? If so, it is likely not the governor but the high pitch stops in the prop.

Yep drops and jumps just fine on the run up, but in cruise I can dial it back to 2250 if it is at a low MAP. Increase the MAP and it will go up to about 2350-ish and that is about it.

So - how low can YOU go? And what prop do you have?
 
Whirlwind 74RV

My Whirlwind 74RV governs down to 1800 RPM in flight with the Jihstrol governor on a parallel valve IO-360.
Cheers
Nige
 
Bill,
I have the Hartzell aluminum BA prop and Johostroj governor. I frequently cruise oversquare at 2300 and 25". Have run as low as 2200 in cruise.

If memory serves, you have the Hartzell composite. And that one has a close approach to the cowl when at high pitch. If adjusting high pitch stop (which I have no clue how or where), don't forget to check that cowl clearance again.
 
My Whirlwind 74RV governs down to 1800 RPM in flight with the Jihstrol governor on a parallel valve IO-360.
Cheers
Nige

This is what I had expected! Thanks

Bill,
I have the Hartzell aluminum BA prop and Johostroj governor. I frequently cruise oversquare at 2300 and 25". Have run as low as 2200 in cruise.

If memory serves, you have the Hartzell composite. And that one has a close approach to the cowl when at high pitch. If adjusting high pitch stop (which I have no clue how or where), don't forget to check that cowl clearance again.

Yes I do have that Hartzell composite, something is just not right. I did not change the prop pitch stops. I sent a note to Hartzell and will follow with a call today. When I took the top off the gov during the clocking process, it seems there is no magic, just a flyball governor. I just wonder if the pressure/flow requirement is different for that wide blade.

What is weird is RPM changing when remaining at the same altitude and everything fixed. I was doing some 3 leg ASI testing and the RPM would wander. I just increased to a stable point and flew on.

I'll contact Team Aerodynamics, they had this prop, maybe Hartzell gov's too. Maybe Kahuna has some knowledge of this.

Update: 5/31/18 Emailed Kahuna, no issues with the Team! So, not likely the prop demand. It would make sense that H would design all props with the same range of pressure demand.
 
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What do you get as a max static RPM? If your brakes won't hold that, what do you get as max RPM right about the time you are lifting off?

If you aren't getting 2650-2700 RPM you may not have the stops set correctly on the propeller. The manual tells you how to do this.

Of course, do make sure you have the prop governor set full forward in the right direction at the governor.

Vic
 
I will be checking the stop - at least the low pitch.

What do you get as a max static RPM? If your brakes won't hold that, what do you get as max RPM right about the time you are lifting off?

If you aren't getting 2650-2700 RPM you may not have the stops set correctly on the propeller. The manual tells you how to do this.

Of course, do make sure you have the prop governor set full forward in the right direction at the governor.

Vic

It usually is right at 2700 on TO and climb or cruise when requested. It started a little low (2650) and I adjusted it up (2700). I will be checking the static RPM of the prop tomorrow. With a density altitude of 3200' on the ground (540 ASL), I am not sure what I should expect for static rpm with the governor out of the picture. I suppose I'll just run to 2700 and note the MAP.

I did reclock the RPM stop suggested by Hartzell and it lowered the set point from 2400 to 2300. It stopped there.

I did check the pitch range of the prop when installed using air pressure. It was the same as the Hartzell test sheet.

Any governor experts, please provide some insight, thanks.
 
Prop speed

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.
 
This is what I had expected! Thanks



Yes I do have that Hartzell composite, something is just not right. I did not change the prop pitch stops. I sent a note to Hartzell and will follow with a call today. When I took the top off the gov during the clocking process, it seems there is no magic, just a flyball governor. I just wonder if the pressure/flow requirement is different for that wide blade.

What is weird is RPM changing when remaining at the same altitude and everything fixed. I was doing some 3 leg ASI testing and the RPM would wander. I just increased to a stable point and flew on.

I'll contact Team Aerodynamics, they had this prop, maybe Hartzell gov's too. Maybe Kahuna has some knowledge of this.

Update: 5/31/18 Emailed Kahuna, no issues with the Team! So, not likely the prop demand. It would make sense that H would design all props with the same range of pressure demand.

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
 
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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. :confused:

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.

K-8pYGdDlKUG71g26ovXbnsfKhq9hoDZMSQ7vXGr7BGr0hid7WJ4bLI2_fJmV8FWJEoRQWL4NYqLBiM58TuemRz4YN1rAnurOlc1FtCml6-taxryEc7SWQnaUwumg1DourUBEX63QTRO6EGNMjiGqr0MWMIvxfyuvXL3hD1ECqT61EP4EDpHU-vcJs7JQM3PluTf0-HsmxTJo2IyJw0d1ce7U8WKBeT9AQJ_7uaRlnxZ2nWavPQWOmLr3HkAi2bLZLm_5owep9pFT706w6OxIb-Sa9OFnwxlL_A9iDiandB4nI_yu_jLzWlwDV_Y4X69983dYAykcocfQZCZW1lP1ef5vkp4taEyC_pxm7zPVVK8yQLTE7dy5M0_Ya4bhMM4a4CmeVFc2zYkojdoWq1xgi6-DhhcOTPf91-7R0okypjGxKoeLyf0vce-v9PDSNjcaCZeT2ZBwVG4lujSo15v8DE8g-i4QeOf_6hhyW2OfsRifUSl6eniTBxFuxCDfL6uHdr-9c3nxjDL_uEqpOfG_aU0M9spzqCnrCi7OWWcfmsqA8Z9-hwTx8VyNPtTSRqvD6Ms1xT1OxYBTbJcuGAPddj1acqKjh--cgMJOzlXUlOuZSXaEj-v9yyZWDxQeUXKkh3zulkn7f2OJN2FrIaWJ8yEP_h1H60z=w545-h726-no
 
Theres a recent thread about engine out procedures where we discussed different govs and their low speed ability wrt windmilling and trying to feather up the prop as best as possible for most glide distance. As I remember, the general consensus was that Hartz govs dont control at a low enough rpm enough to do any engine out prop changes, but MTs and Jihostrofs will. Maybe check that for some numbers...
 
Thanks!!

Theres a recent thread about engine out procedures where we discussed different govs and their low speed ability wrt windmilling and trying to feather up the prop as best as possible for most glide distance. As I remember, the general consensus was that Hartz govs dont control at a low enough rpm enough to do any engine out prop changes, but MTs and Jihostrofs will. Maybe check that for some numbers...

Excellent idea - I just did glide testing and with the engine idling or at ICO, the prop pulled all the way out was consistently 1300+10 RPM.

I did not think about that test when posting.

So for an update, I tested static rpm today and got 2730 at 25' MAP. I took the governor off and found a proper gasket w/screen and no debris.

My wife is tired hearing about this, she said go buy a new governor. No help but it made me feel better. :D

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 did check this today too (just for you), full travel stop to stop, FULL travel.
 
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Have you tried messing with the course pitch stop on the prop? I imagine it's possible that it came from the factory set too aggressive. I am brand new to CS props with my 10 build, but thought I read somewhere that props have both fine and course pitch stops. It seems logical that too tight of a course pitch stop would prevent the governor from getting the RPMs down.

With that said, if you dropped 100 RPM by adjusting the spring, I guess it can't be the stop.

I understand the S series governors have their own pump to up the oil flow to the prop. I could possibly be a mfg defect or improper setup at the factory. As you mention, inadequate oil flow or pressure is a likely suspect.

Larry
 
Update - Not the Governor - it continues.

Well, the education continues.
Short Version:

Engine prop oil transfer ring- not the problem, tested at Lycoming 25 psi, tested by me at 14 psi.

Governor tested by Aircraft Accessories Tulsa, outstanding service and turnaround!! Allen Barrett recommended. Single day turnaround. Perfect settings, per book.

Next steps:

1) Reinstall governor and fly to complete Phase I
2) Extend the discussion with Hartzell to include the high pitch stop (internal) for the prop.
3) Gather data from others with the Hartzell Composite prop as confirmation. Maybe some have other brand governors. My H-composite is 10 fine, 27 coarse.

Next item of focus: high pitch (full pitch) stop

Request:If someone could look in their Hartzell, BA prop book and post or PM with the pitch range from the factory, I would greatly appreciate it.
 
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Bill,
My metal blade, HC-C2TR-1BFP/F7497-2 factory settings were: Low Pitch 13.6, High Pitch 35.0.
I am pretty sure the composite blades are set for less high pitch to avoid contact with the engine cowling at maximum pitch.
I did have to adjust my Low Pitch stop. The high pitch stop is shop adjustable only.

To test this, go up to altitude, WOT, pull the prop back. What is the minimum RPM? Point the nose down, as airspeed increases, does the RPM increase? Point the nose up, as airspeed decreases, does RPM decrease. If those answers are yes, the blades were at maximum pitch.
 
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Perfect

Bill,
My metal blade, HC-C2TR-1BFP/F7497-2 factory settings were: Low Pitch 13.6, High Pitch 35.0.
I am pretty sure the composite blades are set for less high pitch to avoid contact with the engine cowling at maximum pitch.
I did have to adjust my Low Pitch stop. The high pitch stop is shop adjustable only.

To test this, go up to altitude, WOT, pull the prop back. What is the minimum RPM? Point the nose down, as airspeed increases, does the RPM increase? Point the nose up, as airspeed decreases, does RPM decrease. If those answers are yes, the blades were at maximum pitch.

Dave, Sorry I missed your post in a timely manner. I called the former application engineer for Hartzell Props and he called back a couple of days ago. He said the same as you. Likely high pitch stop (probably needs a couple of degrees), and likely due to the sweep clearance of the blade. My next flight will get this test data, just like you described. Thanks!!
 
Prop govt issues.

Slightly off topic here but related.
Recently I have noticed that during run ups I am unable to get the prop to cycle beyond around 100 rpm. It behaves like this on a cold morning and improves once the engine reaches norm operational temps. Thing is it never used to do this regardless of the temp. I'm not talking OAT's below freezing just cold mornings (10degsC) eng/prop around 350 hrs old.
First time I took off after thinking it should be ok I got just ver 2800 rpm (IO360, Hartzell 2 blade) so quickly pulled the rpm back before I rotated, once hot no issues. Any ideas guys?
Thanks.
 
Coarse Pitch Stop - mystery solved

That is the issue, the prop is reaching the coarse/high pitch stop and will not add pitch to go lower in rpm under the specific conditions presented.

The test specified by Les Doud, former prop engineer, to reach the cruise condition then lower the nose - it worked, the RPM went up. This indicates that the coarse/high pitch stop has been reached and more pressure from the governor will not move the prop any more.

It happens at ROP cruise, 8000ft DA and around 163 KTAS. The limit is just above 2300 rpm.

This stop is an internal collar that must be replaced or machined to change the maximum pitch. Les thinks a couple of degrees will work, providing I have the clearance to the cowl to accommodate. I do, well, I should.

This is the question I had first asked the Hartzell Tech line when the "condition" was first presented. Too bad we all had to go thorough this work due to limited preliminary investigation.

I will finish Phase I and then fly to Piqua and get them to do the work on site.

Any Hartzell Composite owners should be aware of this edge of the operating envelope and not get surprised.
 
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