Exercising CS Props

NealRomeoGolf

NealRomeoGolf

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I was reading some Lycoming commentary on cold weather ops on their website and came across this:

"During flight in very low temperatures, exercise constant speed props about every 30 minutes to help prevent congealing of oil in the prop dome."

What would that look like? I typically run at 2400rpm. Does exercising mean bringing it down to 2000? 1800? How far back do you need to pull it according to this recommendation?

I do my pulls during run up but had never heard about exercising a prop in flight.
 
No idea, but exercising could include pushing it forward instead, no?

Plus, what’s “very low temperatures” defined as?
 
455 Bravo Uniform said:
No idea, but exercising could include pushing it forward instead, no?

Plus, what’s “very low temperatures” defined as?
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Didn't say. It was pretty generic. At least their preheat temps are specific. That's what I was there for.
 
"very low temperatures" is pretty subjective.
 
I think the idea is just to move the oil around.. I would do a slow consistent sweep through the normal range
 
NealRomeoGolf said:
I was reading some Lycoming commentary on cold weather ops on their website and came across this:

"During flight in very low temperatures, exercise constant speed props about every 30 minutes to help prevent congealing of oil in the prop dome."

What would that look like? I typically run at 2400rpm. Does exercising mean bringing it down to 2000? 1800? How far back do you need to pull it according to this recommendation?

I do my pulls during run up but had never heard about exercising a prop in flight.
Click to expand...

Never heard that before but it sounds like good idea. I’d say just cycle it like you do on the run up. Maybe not all the way to the stops, just get the oil moving
 
I think this is one of those advisories that doesn't really seem to cause problems. I've spent a lot of time flying piston aircraft in the winter (including the flight levels where the temps were well below freezing, nay, below 0F) and I've never observed any issues with props not behaving as intended due to oil temperature.

Now, one thing that happened on the Aztec was that during icing conditions, the cables going to the prop governor would freeze up. This appeared to be at the prop governor which was located in front of the #2 cylinder on those engines. I also had a few times on that plane where when I started it, the prop cables wouldn't move until the oil warmed up some.

Basically, I wouldn't be worried about it if I were you. But if you do find your prop unresponsive, don't panic.
 
Never heard of doing that. That is something we did not do in Alaska winters, possibly because no one else knew about that either. Most companies I flew for stopped winter operations from -35 to -40 for piston engines. At that temp it does not matter if F or C...:lol:

Then again, most of the legs were less than an hour.

Like others here, I wonder what is considered low temperature. What always concerned me more was first start up in the morning and watching the oil pressure gauge(s) stay at ''0'' until the oil in the line thawed out.
 
I've always done it on runups during cold ops to get the prop moving, it can be sluggish to respond initially. Never thought much about in flight. On the one hand it makes sense, on the other I've never experienced a single problem. I've flown complex planes for hours in cruise temps near 0F.

*On thinking about it again, does doing it every 30 minutes really help much? We always talk about what a great heat sink the prop is in winter. I'd guess the oil probably doesn't hold much heat in the hub for more than a few minutes. You'd almost need continuous flow to make much difference I'd think.

The only oil and cold related issue I've ever heard of in flight is the oil cooler congealing and blocking flow.
 
Zeldman said:
Like others here, I wonder what is considered low temperature. What always concerned me more was first start up in the morning and watching the oil pressure gauge(s) stay at ''0'' until the oil in the line thawed out.
Click to expand...

Yeah, the 310 had one gauge that was slow first start of the day. It was the gauge, even did it when we overhauled the engine. One of my A&Ps got so concerned by it that he broke the glass tapping on it after a cold start.

The Aztec I did a couple of really cold starts in, around 10F, cold soaked overnight, no preheat. The engines would belch to life, almost radial-like, with a lot of smoke and only running on 4-cylinders to start, then 5 would kick in, then 6. It was so cold the fuel flow gauges would read 0 for the first 15-25 minutes.

Of course, you could say that's horrible for the engines (which it was) but at the end of the day those were mostly in the earlier days of my ownership of that plane, and 1,000 hours later they never had any oil-related issues.
 
Bordon tube type oil pressure gauge may have a 20 foot tube connecting it to the engine on a twin, that hole tube full of cold oil that probably acts like peanut butter more than oil.
 
Never heard of cycling a prop in flight and assuming the oil temps are in the normal range I can't imagine needing to. Duct taped oil coolers to increase oil temps are the norm in Alaska.
 
NealRomeoGolf said:
I was reading some Lycoming commentary on cold weather ops on their website and came across this:

"During flight in very low temperatures, exercise constant speed props about every 30 minutes to help prevent congealing of oil in the prop dome."

What would that look like? I typically run at 2400rpm. Does exercising mean bringing it down to 2000? 1800? How far back do you need to pull it according to this recommendation?

I do my pulls during run up but had never heard about exercising a prop in flight.
Click to expand...
Care to share the link for context?
 
My friend you used fly in Alaska talks about flying in temps as low as -40. He was usually more concerned about water normally suspended in the fuel freezing and blocking the screens. Or rubber diaphragms in fuel pumps becoming bittle and breaking. I think -40 qualifies as very low temps. I am trying to remember what temp they usually ceased flight operations at I don't recall if it was -40 or -25 F.
He also advised of some of the issues of flying at a -8000 ft density altitude. Essentially you could easily overboost normally asperated engines and he told me they attributed a number crank failures to this.
Sure there are others here with 1st hand experience with very cold weather ops.
 
brcase said:
My friend you used fly in Alaska talks about flying in temps as low as -40. He was usually more concerned about water normally suspended in the fuel freezing and blocking the screens. Or rubber diaphragms in fuel pumps becoming bittle and breaking. I think -40 qualifies as very low temps. I am trying to remember what temp they usually ceased flight operations at I don't recall if it was -40 or -25 F.
He also advised of some of the issues of flying at a -8000 ft density altitude. Essentially you could easily overboost normally asperated engines and he told me they attributed a number crank failures to this.
Sure there are others here with 1st hand experience with very cold weather ops.
Click to expand...

Those -40 temps are where the water suspended in fuel definitely gets to become a concern. Twin Cessnas (the pressurized ones that will fly in those temps semi-regularly) have been known to have issues with that, so they use oil-heated fuel spiders. Definitely what I'd be concerned about before oil temp.
 
Stewartb said:
Isopropyl fuel additives are advised when temps go cold.
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The filters will pick up ice when it is cold enough. but many run a can of dry gas all season.
 
I think many Props have a Bleed Hole to allow some circulation.

Any Prop Guys on board ?

It was a normal procedure when flying THROUGH weather with some Radial Engine Transports.

Why not do it?

You paid to have a Constant Speed Prop; why would you want an in-flight conversion to Fixed Pitch?
 
Tom-D said:
The filters will pick up ice when it is cold enough. but many run a can of dry gas all season.
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I've pulled many a pick-up filter and finger screen in winter in lots of different fuel tanks. Seeing a coating of slush is common. How fuel flows through that is a mystery but the idea that it may clog is easy to believe. I always add isopropyl in winter. Not just to airplanes, either.

I've never had a sluggish prop in a properly preheated or properly operated airplane.
 
Why would you think the governor isn't always adjusting the props slightly and moving the oil throughout a normal flight? Or are you all holding altitude within a foot, and have no turbulence or other disruption that would cause the prop to adjust during normal flight?
 
A mechanic suggested to me to taxi with the prop pulled all the way back when it is cold to help get the oil moving. Wouldn't this only work if the RPM got high enough to move it off the stops? I know I cycle it more when very cold after a slight overspeed one very cold morning when the oil was too think to make the governor fully work to the full range.
 
I wouldn't matter on the stops. Just be careful during the runup when its cold, give it some time to catch up
 
Ted said:
I think this is one of those advisories that doesn't really seem to cause problems. I've spent a lot of time flying piston aircraft in the winter (including the flight levels where the temps were well below freezing, nay, below 0F) and I've never observed any issues with props not behaving as intended due to oil temperature.

Now, one thing that happened on the Aztec was that during icing conditions, the cables going to the prop governor would freeze up. This appeared to be at the prop governor which was located in front of the #2 cylinder on those engines. I also had a few times on that plane where when I started it, the prop cables wouldn't move until the oil warmed up some.

Basically, I wouldn't be worried about it if I were you. But if you do find your prop unresponsive, don't panic.
Click to expand...

I live in a seriously winter climate. My ambient temperature limit to go flying is 0 deg F (-18 C). Has nothing to do with the plane and everything to do with my lack of desire to subject myself to "excessive hardship in my advancing years" (e.g. I'm becoming soft and lazy :D).

Regularly fly the Aztec at altitudes where the temps are well below zero. Never had an issue with the props. Plane is kept in a heated hangar or the Tanis is plugged in if away. Usual prop checks on runup - AFTER the oil is warmed up, as you noted above.

Magman said:
...Why not do it?

You paid to have a Constant Speed Prop; why would you want an in-flight conversion to Fixed Pitch?
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Not a chance.

I don't change anything in flight that isn't necessary - in other words it's "constant speed". When I come down from cruising altitude and configure for landing the props go to 2400 at 100 knots, then full fine turning final. Has worked every time I've tried it so far. ;) Not motivated to change without a good reason.
 
GRG55 said:
I live in a seriously winter climate. My ambient temperature limit to go flying is 0 deg F (-18 C). Has nothing to do with the plane and everything to do with my lack of desire to subject myself to "excessive hardship in my advancing years" (e.g. I'm becoming soft and lazy :D).
Click to expand...

The companies I worked for in Alaska didn't care about the human cargo onboard in cold temps. It was the small things breaking at -40 that they cared about. Small things like plastic interior pieces, vinyl seats and even door hinge pins. Not to mention listening to the gyros howl and screech in the cold air. But I hear ya.... wearing 40 pounds of clothes to deliver a plane load of Pepsi to a village in the middle of winter is not fun anymore....
 
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