Prop slow to cycle at 1700rpm

Groundpounder

Groundpounder

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Emerson Bigguns
Was doing a run up today, and when I did the prop check at 1700rpm, it was very slow to change RPM, and there wasn't the normal aural and tactile feel that I am used to. Tried it at around 2100rpm and it felt perfectly normal. Any idea what the issue is?

IO-520BB in an F33A.
 
Getting colder out your way? Mine are like that on the governor check when the temps start dropping, but my book says to do the governor check at 2000 RPM (feather check on the twin is at 1500 RPM). On cold days I will cycle them alternately 2 or 3 times if necessary.
 
GRG55 said:
Getting colder out your way? Mine are like that on the governor check when the temps start dropping, but my book says to do the governor check at 2000 RPM (feather check on the twin is at 1500 RPM).
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It is, but it was almost 60* today and I had flown it previously in colder air with a normal run up at 1700 rpm.
 
I do mine around 1900 - 2000.... IO-540 with 3 blade Hartzel
 
How many times did you cycle it?

Sometimes if it’s cold or I haven’t flown in a bit it will be slow at first, the next two will he just fine.

I’d also push it back forward the second you hear it catch
 
I also cycled it at 1700 on the taxi in when I landed, and it still seemed slow. It was about a 15 min flight.
 
Groundpounder said:
I also cycled it at 1700 on the taxi in when I landed, and it still seemed slow. It was about a 15 min flight.
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Sounds like something has changed then, and worth getting checked out. Oil seal in the governor perhaps? Or something binding in the mechanical linkage?
 
I didn't notice any oil in odd places, gave it all a good once over after I landed. It is down for ADS-B for a few weeks, I will drop a line to my mechanic and see what he thinks.
 
How long since prop and/or governor overhaul?
 
Bill Jennings said:
How long since prop and/or governor overhaul?
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~150 hours.

Spoke with my mechanic. Said its most likely due to the cooler air temps, and that generally 1700 rpm is low for a prop cycle check to begin with. He said to keep an eye on it and if I see any other changes to let him know.
 
Groundpounder said:
~150 hours.

Spoke with my mechanic. Said its most likely due to the cooler air temps, and that generally 1700 rpm is low for a prop cycle check to begin with. He said to keep an eye on it and if I see any other changes to let him know.
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Advice sounds good to me, especially if you're running straight weight oil, vs multi-vis.
 
Had this problem in a 182, which gradually got worse until it wouldn't cycle at all even at more than 2000 rpm. Turned out to be a loose cable.
 
Cycling the prop at 1700 proves the governor will dump but that does not necessarily prove proper governor function. RPM must be above that. Cycling the prop to 1800 from 2000 shows that it is governing to 1800. As a mechanic I listen to pilots deep cycling from high RPM and doing it multiple times. Not necessary. This puts unnecessary strain on the airframe and guarantees dings on the leading edge of the prop.
 
charlie said:
Cycling the prop at 1700 proves the governor will dump but that does not necessarily prove proper governor function. RPM must be above that. Cycling the prop to 1800 from 2000 shows that it is governing to 1800. As a mechanic I listen to pilots deep cycling from high RPM and doing it multiple times. Not necessary. This puts unnecessary strain on the airframe and guarantees dings on the leading edge of the prop.
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While my plane was in annual, taking a break with 2 senior IA’s and an A&P, everyone cringed hearing the local flight school across the ramp deep cycle props. There is no need to stress the system like this. The objective is flushing warm oil into the hub. Many consider a best practice to quickly move the prop control briskly in and out watching the oil pressure gage wiggle a bit, demonstrating oil is flowing but not slow enough to materially change RPM. If it makes someone feel better, after this pull the prop slightly for no more than a 300 rpm drop.

Others may have better techniques, but this works great and keeps stress low on hub, regular, etc.
 
Thanks.

I was taught to start at 1700 (or 2000, or whatever the poh says), then briefly pull it back a few hundred rpm, and to repeat it a few times, noting mp/oil pressure along the way. Sounds like this is an OWT.

When I recently flew with someone else (who also happened to be an A&P), when I went to push the prop back in, he told me to pull it back and leave it there to make sure the governor holds.
 
Our prop is cycled at 2000. My partner and I differ on methods. He just pushes in the button and pulls it out to the stop as quickly as he can, then zip back in. Repeat. I think that is too abusive. I pull slowly just until I detect an RPM drop, then back in. Don't know who's method is better, but I just don't like the quickly pull it all the way out thing...
 
If it's been a while since the prop has been off, the crankshaft builds up muck inside the prop to crank area scoop the sludge out.
 
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