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Prop cycling

sailvi767

Well Known Member
I read one of John Deakins articles where he recommends not cycling the prop on single engine aircraft during preflight checks. During shutdown most of the oil is pushed out of the hub so he states there is no need to move oil through the hub and watching the prop RPM on takeoff power application is more than a sufficient check. He has different advice for feathering props. I always only cycled my prop once rather than multiple cycles I see many accomplish but this has me thinking about if I should do it at all. Thoughts?
 
As the new owner of a Hartzell prop I was wondering the same thing. I would think at least once to check for proper function on run-up.
 
I never do it as it serves no useful purpose as far as I can tell.
The prop worked fine during the last flight, so why not the next.
I also don't think loading up a cold engine with excess prop pitch is a great idea at low RPM.
 
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I cycle the prop once, but only once. Once, after a wintertime oil change, I warmed my engine oil to over 100 degrees then cycled the prop. It didn't cycle! I tried it again and it worked fine thereafter. For me, this just seems the right thing to do, and I don't think I'm hurting anything accomplishing the check.
 
on a previous aircraft noticed the Hartzell governor arm had fractured whilst doing that very check...
Now on the MT I do 2 slight drop cycles and only once a day.
 
If I let my airplane sit for 2 weeks it takes several seconds for the prop to cycle for the first time. Flying daily it doesn't do this.
 
I was told that other than testing operation, the triple cycle was to ensure warm oil in the hub so I've always done that. If there is no merit to it, I can certainly be convinced to change my mind.
 
I cycle 3 time on the first flight of the day, then once on every flight after that. I wait just long enough to hear the engine change and see the RPM drop on the panel.

-Marc
 
I cycle once on the first flight of the day for VFR ops. I cycle each takeoff for actual IMC departures. I'm not so much worried about cold oil in the hub as I am about catching a failing (or failed) component.
 
I'm not convinced about the warm oil idea, the prop hub oil does not circulate, it only adds or subtracts a little oil to change the pitch a little bit during normal flight operations. The propeller hub oil temperature must certainly be very close to the ambient air temperature.
I have upgraded the blades on my Yak-55, which included removing the propeller pitch dome. Inside (after the expected liter of oil poured out) I found a ring of carbon crud. This is centrifugally deposited and lays next to the oil seal. Every hydraulic constant speed propeller must be like this.
The oil enters and departs the hub thru a tube in the center, so carbon deposited must be manually removed. The fewer times the prop is cycled, the fewer times carbon is deposited.
I cycle the prop twice before take-off because I want to know that it works.
I'll probably remove the piston dome on the next condition inspection to inspect the parts and clean the carbon out.
https://www.monoplaneforum.com/viewtopic.php?f=58&t=192
a link to the monoplane forum where I have a few pics of the prop blade upgrade and the carbon inside the prop pitch actuator.
 
What does the propeller manual from the manufacturer say?

The Hartzell manual gives instructions on prop checks during run-up in the Inspection and Check chapter, section 3, paragraph B.
 
I read an article years ago about this. As I remember it one of the reasons for cycling the prop was to change the oil in the hub to prevent deposits from building up. If you want to check the operation of the governor it seems to me you would pull the prop control back some to the point where it doing some controlling and advance the throttle up to see if the rpms hold. Hope this makes sense.
 
I only move my elevator two inches each way before take-off to make sure it works.. Hope this helps. 🙄
 
Not that it matters to your comment, but . . .

I'm not convinced about the warm oil idea, the prop hub oil does not circulate, it only adds or subtracts a little oil to change the pitch a little bit during normal flight operations. The propeller hub oil temperature must certainly be very close to the ambient air temperature.
I have upgraded the blades on my Yak-55, which included removing the propeller pitch dome. Inside (after the expected liter of oil poured out) I found a ring of carbon crud. This is centrifugally deposited and lays next to the oil seal. Every hydraulic constant speed propeller must be like this.
The oil enters and departs the hub thru a tube in the center, so carbon deposited must be manually removed. The fewer times the prop is cycled, the fewer times carbon is deposited.
I cycle the prop twice before take-off because I want to know that it works.
I'll probably remove the piston dome on the next condition inspection to inspect the parts and clean the carbon out.
https://www.monoplaneforum.com/viewtopic.php?f=58&t=192
a link to the monoplane forum where I have a few pics of the prop blade upgrade and the carbon inside the prop pitch actuator.
Scott, typically the deposits are lead from the fuel that has made its way into the oil. It gets really hard from the centrifugal forces. Centrifugal oil filters do the same thing. They do collect carbon when applied to diesel engines with higher particulate (soot) production.

I suppose it could be carbon on a specific engine if the oil generates carbon particles from contact with high temperature interior surfaces. Not typical though.
 
Every constant speed prop Certified AC I know of (a few dozen both single and multi) AFM/POH all call for you to cycle the prop during run up...

With that said DO NOT DRAG RPM DOWN.... I pull the blue knob back and smoothly push forward almost before the Prop starts to react.... Sure once is OK. I get a drop of a few 100 RPM before it is going back to fine pitch/high RPM. You are checking function of the Prop control, governor not just getting oil into the prop. On that same note why check carb heat, ignition, flight controls, fuel pump? Why run up at all, kick the tires light the fire? This is a rhetorical question to make a point. Don't reinvent the wheel, check the Prop function. It does not hurt anything, just don't LUG the engine RPM down.
:D
 
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It's necessary to get the system liquid full, and secondly to assure control effectiveness. Others I'm sure are much more nervy than me, but having the propeller surge when climbing out cured me early on of not cycling it before takeoff. And I never flew a government certified recip that didn't specify cycling the prop before takeoff.
 
I spoke to Hartzell about this a few months ago and they stated the reason to cycle the prop is to expel any air that might be present in the system. When the engine is shut down the oil drains back causing a slight negative pressure in the system and it is possible that air will come in through one of the seals.
 
It's necessary to get the system liquid full, and secondly to assure control effectiveness. Others I'm sure are much more nervy than me, but having the propeller surge when climbing out cured me early on of not cycling it before takeoff. And I never flew a government certified recip that didn't specify cycling the prop before takeoff.

Surging is often caused by the low pitch stop not being adjusted correctly, the prop overspeeds while the gov attempts to catch it.
I hear this quite often on RV's when they take off.
 
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