CS prop and cycling

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onwards

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onwards
So the other day I took the 182 out for a quick flight, after a couple of cold days. Went through the normal routine, got to runup, put it up to 1700RPM, pulled the prop... and nothing.

Tried it again. Nothing.

Sighed heavily, taxied to the mechanics shop, asked him to take a look, figured the governor or maybe the cable must be broken.

He took off the cowl, checked everything, looked fine. Said let's try again. Same thing. Then he says "try 1900RPM instead".

Voila! everything working as expected.

Turns out when it's really cold, the oil takes a longer time to warm up, which can impact the ability of the prop governor to create the pressure necessary for this check to succeed, or something along these lines. Anyway, I learned something new, but also wonder if someone here is willing to try and explain this better?
 
are you waiting for the oil to get into the green on the temp gauge? I wait until I get over 105 before doing runup.
 
That happened to me once. Got out of the plane, and there was oil all over the ground.
 
Makes me so glad I left New Jersey and ended up in Florida.:goofy:
 
onwards said:
He took off the cowl, checked everything, looked fine. Said let's try again. Same thing. Then he says "try 1900RPM instead".

Turns out when it's really cold, the oil takes a longer time to warm up . . .
Click to expand...

Did you just created a ton of cavitation in your oil pump inlet by doing this, or I'm just being an ignorant paranoic?
 
Doesn't a prop governor get its oil from its own small pressure boosting pump, which is in turn gets its oil from the engine oil pump? I agree it sounds like something is not flowing oil.

Oil flow in an aircraft engine initially has little access to the heat of the cylinders etc. In other words, the oil can't warm up much until it starts to flow out of the main and rod bearings - and that isn't going to happen until the oil warms up.......
 
nrpetersen said:
......to flow out of the main and rod bearings - and that isn't going to happen until the oil warms up.......
Click to expand...

:yikes::hairraise:..

The oil better be flowing out the rod and main bearings with 3-5 seconds after start up or the motor is TOAST...:yes:
 
I have been told by some old salts not to yank the the prop control back indiscriminately with really cold oil as the viscous oil will cause the governor to max out the pressure in the hub and cause leaks. Now, this is from folks who fly in the frozen north for 60+ years, so there may be some truth to it.

Btw, by just pulling the prop back, you are not really testing much. For your test to include the governor, run the engine up to 2100rpm, pull back the prop to 2000 and then advance the throttle. If the rpm holds at 2000 and you feel the 'pull' of the governor taking the prop out of fine-pitch, you know that not only does the piston/linkage thing in your prop move but you also know that the governor itself is governing.
 
Maxwell Propeller Service taught me the best prop cycle warm up is to do it at a lower RPM (as low as it will cycle, but no more than 1400 RPM) and let it sit in high pitch for 10-15 seconds to let the warmer oil thoroughly cycle though the hubs. They said the high RPM cycles just stress parts without accomplishing the goal of warm oil to the hub.
 
onwards said:
So the other day I took the 182 out for a quick flight, after a couple of cold days. Went through the normal routine, got to runup, put it up to 1700RPM, pulled the prop... and nothing.

Tried it again. Nothing.

Sighed heavily, taxied to the mechanics shop, asked him to take a look, figured the governor or maybe the cable must be broken.

He took off the cowl, checked everything, looked fine. Said let's try again. Same thing. Then he says "try 1900RPM instead".

Voila! everything working as expected.

Turns out when it's really cold, the oil takes a longer time to warm up, which can impact the ability of the prop governor to create the pressure necessary for this check to succeed, or something along these lines. Anyway, I learned something new, but also wonder if someone here is willing to try and explain this better?
Click to expand...

First it is very possible that the cold oil just took a bit longer to get warmed up, and flow thru the governor.

So, did you fly? Any problems controlling engine speed in flight?

Is your prop cycling at its "normal" run up speed now?

zaitcev said:
Did you just created a ton of cavitation in your oil pump inlet by doing this, or I'm just being an ignorant paranoic?
Click to expand...

No the governor will still pump oil even if it is not putting it into the hub.

nrpetersen said:
Doesn't a prop governor get its oil from its own small pressure boosting pump, which is in turn gets its oil from the engine oil pump? I agree it sounds like something is not flowing oil.
Click to expand...

The governor is its own pump. It just moves oil into or out of the prop hub.

weilke said:
I have been told by some old salts not to yank the the prop control back indiscriminately with really cold oil as the viscous oil will cause the governor to max out the pressure in the hub and cause leaks. Now, this is from folks who fly in the frozen north for 60+ years, so there may be some truth to it.
Click to expand...

No argument there, the governor has a pressure relive valve, but cold parts do funny things sometimes.

weilke said:
Btw, by just pulling the prop back, you are not really testing much. For your test to include the governor, run the engine up to 2100rpm, pull back the prop to 2000 and then advance the throttle. If the rpm holds at 2000 and you feel the 'pull' of the governor taking the prop out of fine-pitch, you know that not only does the piston/linkage thing in your prop move but you also know that the governor itself is governing.
Click to expand...

Sure you are. If the prop cycles then the governor is moving oil into or out of the prop. Show you that it is working. You can test it that way if you want, nothing wrong with it other than many manufactures check lists don't require it.

LDJones said:
Maxwell Propeller Service taught me the best prop cycle warm up is to do it at a lower RPM (as low as it will cycle, but no more than 1400 RPM) and let it sit in high pitch for 10-15 seconds to let the warmer oil thoroughly cycle though the hubs. They said the high RPM cycles just stress parts without accomplishing the goal of warm oil to the hub.
Click to expand...
I don't really like this. I don't think is good to run the engine at high pitch low RPM like that. Just an opinion. Next once the hub is in high pitch it is in a state of equilibrium against the counter weights, so no more oil is going to be pumped into it. Cycling is much better, oil in/oil out.
Just my 2 cents
 
flyingmoose said:
I don't really like this. I don't think is good to run the engine at high pitch low RPM like that. Just an opinion. Next once the hub is in high pitch it is in a state of equilibrium against the counter weights, so no more oil is going to be pumped into it. Cycling is much better, oil in/oil out.
Just my 2 cents
Click to expand...

Just sharing what the guy said that's been rebuilding them for fifty years. But maybe he's just trying to generate work? :dunno:
 
flyingmoose said:
First it is very possible that the cold oil just took a bit longer to get warmed up, and flow thru the governor.

So, did you fly? Any problems controlling engine speed in flight?

Is your prop cycling at its "normal" run up speed now?
Click to expand...

Yes. No. Yes.
 
In the 182, if it's cold and it hasn't been flown for a week or three, it'll take a few seconds to respond on the first cycle sometimes. I pull the prop lever back, wait for the RPM to start to reduce, push it back in. The second time, it generally comes right back, at which point I know it's ready to go.

How long did you wait for it to do something?
 
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