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Old 10-19-2018, 07:17 PM
sglynn's Avatar
sglynn sglynn is offline
Join Date: Mar 2008
Location: Anacortes, WA
Posts: 778
Default First test of CS prop. Not sure its working.

So I'm not sure my new constant speed prop is working. I'm almost done with RV-7A with IO360 engine and prop from Van's. I did the second idle test today to make sure both mags are working and to see if CS prop is working. I stayed at 1000 "RPM and only ran engine for a couple minutes to keep temperatures low until I'm ready to break in. But at 1000 RPM I pulled the Prop cable like I do on my Cherokee at 2,000 RPM and looked for RPM slow down. I got no change. I pulled a little farther, no change. I didn't get any noticeable difference pulling the prop back at idle. Shouldn't I though? I checked the cable and yes it is pulling the governor fully. And yes I can twist the blades by hand. Maybe there is a lot of new oil that needs to run up into the hub and I didn't give it a chance.

So, what's your experience? How does the first tests of your CS Props go? What do you think I should try in order to make sure it is hooked up properly and working?

Steve Lynn
Flying Phase I
Anacortes, WA
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Old 10-19-2018, 07:19 PM
BillL BillL is online now
Join Date: Sep 2007
Location: Central IL
Posts: 5,021

Try it at 1700 before getting concerned. It may take a while to get the air out and fill the passages with oil. 4 or 5 slow pulls all the way out. Mine really jumps when pulling the prop and hard to hold, so be ready.

1st Flight 1-27-18
Phase II 8-3-18
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Last edited by BillL : 10-20-2018 at 05:32 AM.
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Old 10-19-2018, 07:51 PM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 11,925

Our four C/S Prop installations all have different “minimum reaction RPM’s”. One you can cycle at 1800, one has to be at 1850, another wants 1900, and the fourth won’t cycle until you get it to 1950. None of them would even come close to cycling at 1,000 rpm.
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
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Old 10-19-2018, 08:45 PM
pilotkms pilotkms is offline
Join Date: Mar 2007
Posts: 311

My Hartzell prop with Hartzell governor will NOT cycle at 1300 or below. I haven’t looked for the exact rpm spot where it transisions but it will cycle at 1600 and above.
RV 7A RV #9700 May 2017
N325KS the Flying “K”
Built in SoCal KCCB, now in GA @ KPXE
375+ Hours & 7X cross the USA
OSH flyin 2018 & 2019
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Old 10-20-2018, 06:50 PM
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airguy airguy is offline
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 4,674

My Whirlwind prop (Jihostroj governor) won't pay attention below about 1400 rpm, and then very sluggishly. On top of that you've got large air bubbles in the system with a new install that you will have to purge with a few cycles first.

Start with a cool engine and get the rpm up around 1800 and give it a few seconds, I think you'll be fine.
Greg Niehues - PPSEL, IFR, Repairman Cert.
Garden City, TX VAF 2019 dues paid
N16GN flying 450 hrs and counting! Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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Old 10-21-2018, 08:02 PM
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gmcjetpilot gmcjetpilot is offline
Join Date: Jan 2005
Posts: 3,857

Ditto the prop will not change pitch at low RPM... as folks say above. I don't think there is a specific RPM it will work or not work... it is a function of oil pressure. I would not attempt to cycle the prop at low RPM. The min should be run up RPM, 1700 RPM.
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767
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Old 10-21-2018, 08:11 PM
Bicyclops Bicyclops is offline
Join Date: Oct 2012
Location: LA, California
Posts: 244

I didn't bother cycling the prop til I had an hour on the engine. First flight I just left everthing forward and worked on breaking in. When it came up to 2700 on the takeoff roll, I figured that it was working well enough and left it alone. Why draw oil pressure away from servicing the bearings before they even have a chance to begin wearing in?

Ed Holyoke
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Old 10-22-2018, 05:14 AM
schaplerrh schaplerrh is offline
Join Date: Mar 2014
Location: Alexandria VA
Posts: 290

CS props at low rpm (low MP) work like a fixed pitch propeller so there’s going to be no rpm change without a throttle change at lower power settings.
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