Feathering Single Engine

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JC150

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JC150
Having a debate with some other pilots and I wanted to see what you all thought on here. I know piston singles can't be "feathered", but would it be beneficial to pull the blue lever back during an engine failure that way there's less drag? This is assuming it's done while there's still some oil pressure left to change the pitch of the prop.

One of the pilots I spoke with said he's had 7 engine failures in a piston single, and all 7 times he's pulled the blue lever back all the way.

Curious what others think about this.
 
JC150 said:
Having a debate with some other pilots and I wanted to see what you all thought on here. I know piston singles can't be "feathered", but would it be beneficial to pull the blue lever back during an engine failure that way there's less drag? This is assuming it's done while there's still some oil pressure left to change the pitch of the prop.

One of the pilots I spoke with said he's had 7 engine failures in a piston single, and all 7 times he's pulled the blue lever back all the way.

Curious what others think about this.
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Go up and try it some time. It makes a noticeable difference.
 
I agree. I remember doing it in the CE208 and it felt astoundingly different. That's an enormous prop so It really accelerated when the drag was reduced.
 
I'm certainly not gonna go out there and pull the red knob in flight and test the theory out, but my understanding is that pulling the prop on an idling engine, and pulling the prop on a non-firing engine are significantly different conditions. You don't have any oil pressure of consequence on a windmilling engine, the way you do an idling engine. Ergo, you're nowhere near being able to pull it flat enough to effect a reduction in drag absent ignition the way you can when doing that same prop lever pull with a idling(firing) engine.

Which makes sense, given that when flying circa best glide speed, the kind of RPM you attain on a windmilling engine is low enough to not even reach the governable range of the prop in the first place. But I may be wrong, maybe you do have oil pressure of consequence. Like I said, I'm not gonna go test it out. My hershey bar arrow sucks at gliding. I've always assumed a 1:1 thousand foot/NM ratio and just figured I'll crash where I crash. Making paved fields is not a real priority of mine in this brick glider.
 
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hindsight2020 said:
I'm certainly not gonna go out there and pull the red knob in flight and test the theory out, but my understanding is that pulling the prop on an idling engine, and pulling the prop on a non-firing engine are significantly different conditions. You don't have any oil pressure of consequence on a windmilling engine, the way you do an idling engine. Ergo, you're nowhere near being able to pull it flat enough to effect a reduction in drag absent ignition the way you can when doing that same prop lever pull with a idling(firing) engine.

Which makes sense, given that when flying circa best glide speed, the kind of RPM you attain on a windmilling engine is low enough to not even reach the governable range of the prop in the first place. But I may be wrong, maybe you do have oil pressure of consequence. Like I said, I'm not gonna go test it out. My hershey bar arrow sucks at gliding. I've always assumed a 1:1 thousand foot/NM ratio and just figured I'll crash where I crash. Making paved fields is not a real priority of mine in this brick glider.
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The oil pump is turned mechanically by a gear inside the engine. Doesn't matter if the spark plugs are sparking or the fuel is flowing, if the engine is turning the oil pump is making pressure (assuming it's not the part that failed). Whether or not the engine is spinning fast enough to be in the range of the governor is a good question, but oil pressure will be the same regardless of windmilling or idling given the same engine rpm.
 
There are a few single engine aircraft that are able to feather the prop. The Mooney Missile and Rocket conversions, for instance. Loss of oil pressure would take it into feathered mode.
 
It will not adversely affect your glide. It will either help or do nothing so if you're high enough to have the extra couple of seconds to pull ..... why not?
 
JC150 said:
Having a debate with some other pilots and I wanted to see what you all thought on here. I know piston singles can't be "feathered", but would it be beneficial to pull the blue lever back during an engine failure that way there's less drag? This is assuming it's done while there's still some oil pressure left to change the pitch of the prop.

One of the pilots I spoke with said he's had 7 engine failures in a piston single, and all 7 times he's pulled the blue lever back all the way.

Curious what others think about this.
Click to expand...

I think I'd be hesitant to take engine operating advice from someone who has had seven engine failures in a piston single.
 
roncachamp said:
I think I'd be hesitant to take engine operating advice from someone who has had seven engine failures in a piston single.
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Hey, he lived this far - his advice has to be worth something, over someone who had not survived!
 
hindsight2020 said:
I'm certainly not gonna go out there and pull the red knob in flight and test the theory
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I know someone who did, many times (Viking; IO-520) to prove the theory - he had some numbers which I don't recall, but there was a marked difference in glide distance at the same rate of descent.
(He did not take it to touchdown, he restarted each time.)
 
Always been told to pull it back.

There's absolutely no reason not to regardless and if you have the oil pressure to move it, it should reduce drag. Ask yourself this. If you are in that situation, are you really going to think "ok, do I have enough oil pressure for this to matter?"

No, you aren't. Pull the stupid thing back in the one second it takes to do so and it either works or it doesn't. But it can only help.
 
JC150 said:
One of the pilots I spoke with said he's had 7 engine failures in a piston single, and all 7 times he's pulled the blue lever back all the way.
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Is it 7 0r 9 lives a kitty has, and does that apply to engine failures as well? Seven. engine. failures. wow.

May I suggest a Cirrus for your friend?
 
Norman said:
I could add to the conversation, but sure as hell, someone (you all know who) would say I' don't know what I'm talking about.
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May as well, he's gonna say it anyway.
 
Let'sgoflying! said:
Hey, he lived this far - his advice has to be worth something, over someone who had not survived!
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Fair point. Maybe I'd take advice from him on how to set down a plane with a crippled/blown engine. But not on proper engine management.

7 ENGINE FAILURES? I hate to say this with absolutely no evidence, but I'm not completely sure I believe that. Unless he is a bonafide test pilot.
 
He could be a pilot with tons of single engine time combined with being a bit of a statistical anomaly.
 
SkyDog58 said:
He could be a pilot with tons of single engine time combined with being a bit of a statistical anomaly.
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Or maybe he uses one of those A&Ps that tend to ignore the grey areas.
 
SkyDog58 said:
He could be a pilot with tons of single engine time combined with being a bit of a statistical anomaly.
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My CFI has just under 40,000 hours. Flew crop dusters early on in life. I think he's had 3 engine failures total.

7 just seems like a crazy number. I think I'd retire from flying at around 5 or so.
 
Well, here goes. On a non-feathering prop, once the engine RPM is below the point where the governor can develop enough pressure to keep it in the coarse position it's going to revert to it's normal position, which is flat pitch. The reverse would be true on a feathering prop, and it would settle at coarse pitch unless it was feathered while still having sufficient RPM to accomplish that.

OK. I'm waiting for the rebuttal. :mad2:
 
JC150 said:
Having a debate with some other pilots and I wanted to see what you all thought on here. I know piston singles can't be "feathered", but would it be beneficial to pull the blue lever back during an engine failure that way there's less drag? This is assuming it's done while there's still some oil pressure left to change the pitch of the prop.

One of the pilots I spoke with said he's had 7 engine failures in a piston single, and all 7 times he's pulled the blue lever back all the way.

Curious what others think about this.
Click to expand...
Here's the thing about most piston single engine constant speed props: they tend to be setup opposite of twins in that low oil pressure drives the blades toward flat pitch.

Whether or not you can bring the pitch on a single back to reduce drag after an engine failure depends largely on the nature of the engine failure. If you still have sufficient oil pressure, then yes, you can pull the prop back and it will extend your glide.

But there is a catch. While it may extend your glide, it will also extend your landing distance. Which can be problematic when you start to flare normally and the airplane keeps eating up runway.

I am a big believer in train like you fight, fight like you train. If you train simulated engine failures with flat pitch and you are comfortable with putting the airplane down precisely where you want it in that configuration, then stick with what you know if and when the real emergency comes along. The most important part of dealing with an engine out landing is maintaining control of the aircraft all the way into the landing wherever that may be. What often kills people in those situations is trying to extend the glide to make a better landing point. So, I generally don't advocate pulling the prop back as a normal course of action.

Now, if you are at high altitude cruising over hostile terrain like the Rockies, then by all means, do everything you can to extend your glide to friendlier country.
 
Norman said:
Well, here goes. On a non-feathering prop, once the engine RPM is below the point where the governor can develop enough pressure to keep it in the coarse position it's going to revert to it's normal position, which is flat pitch. The reverse would be true on a feathering prop, and it would settle at coarse pitch unless it was feathered while still having sufficient RPM to accomplish that.

OK. I'm waiting for the rebuttal. :mad2:
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I don't think that is right. When the engine is running, both twins and singles work the same way: When you pull the power back in the pattern to land, the prop gets to its low pitch limits (flat pitch) and you can push the rpm lever all the way forward with no change in RPM. This is why a lot of us don't push the prop forward until short final (easier on both the engine and the neighbors below).
 
StinkBug said:
if the engine is turning the oil pump is making pressure (assuming it's not the part that failed).
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That is kind of the key part right there. If the engine failed because of no oil pressure, then you will not have any control over the prop and why you can't count on being able to pull the prop back for every engine failure in a single.
 
Norman said:
Well, here goes. On a non-feathering prop, once the engine RPM is below the point where the governor can develop enough pressure to keep it in the coarse position it's going to revert to it's normal position, which is flat pitch. The reverse would be true on a feathering prop, and it would settle at coarse pitch unless it was feathered while still having sufficient RPM to accomplish that.

OK. I'm waiting for the rebuttal. :mad2:
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WTF Norman! What a load of BS!.jpe . You don't know what the **** you're talking about! ;)
 
There seems to be a lot of comments about the 7 engine failures. He ferries airplanes for a living and has over 20,000 flight hours. In those 7 engine failures in a piston single, he has been able to land at an airport everytime.

So, what I'm getting from this is pulling the blue knob back can only help, not hurt, so why not?
 
JC150 said:
There seems to be a lot of comments about the 7 engine failures. He ferries airplanes for a living
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Maybe if you had mentioned that in your post we wouldn't have so many comments about it. :rolleyes:
 
If you are flying "iffy" airplanes for a living, (as some of us have done to pay the bills) seven engine failures is not out of the norm.
 
Norman said:
Well, here goes. On a non-feathering prop, once the engine RPM is below the point where the governor can develop enough pressure to keep it in the coarse position it's going to revert to it's normal position, which is flat pitch. The reverse would be true on a feathering prop, and it would settle at coarse pitch unless it was feathered while still having sufficient RPM to accomplish that.

OK. I'm waiting for the rebuttal. :mad2:
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This was my thought, as well. If you feather the prop, it is not going to windmill for very long. That's the whole point of feathering it in the first place, to lose the drag of the windmilling prop. Once it stops windmilling, the oil pump stops turning and you lose pressure, which results in the prop return springs (or whatever mechanism is inside the magical prop hub) forcing the blades fine, which returns the drag. But then it may windmill again and build oil pressure back up. So...does it find a point of equilibrium? It sounds to me like, even if it did, you are trying to extract energy from the prop's drag through the air which means more drag than if you don't try to extract energy from it.

So that means to me that you likely get no benefit from pulling the prop lever back. And the only way to know for sure is going to be an experiment, which means the same airplane and pilot actually killing the engine in flight on multiple occasions. I call "not it."
 
Fearless Tower said:
Here's the thing about most piston single engine constant speed props: they tend to be setup opposite of twins in that low oil pressure drives the blades toward flat pitch.

Whether or not you can bring the pitch on a single back to reduce drag after an engine failure depends largely on the nature of the engine failure. If you still have sufficient oil pressure, then yes, you can pull the prop back and it will extend your glide.

But there is a catch. While it may extend your glide, it will also extend your landing distance. Which can be problematic when you start to flare normally and the airplane keeps eating up runway.

I am a big believer in train like you fight, fight like you train. If you train simulated engine failures with flat pitch and you are comfortable with putting the airplane down precisely where you want it in that configuration, then stick with what you know if and when the real emergency comes along. The most important part of dealing with an engine out landing is maintaining control of the aircraft all the way into the landing wherever that may be. What often kills people in those situations is trying to extend the glide to make a better landing point. So, I generally don't advocate pulling the prop back as a normal course of action.

Now, if you are at high altitude cruising over hostile terrain like the Rockies, then by all means, do everything you can to extend your glide to friendlier country.
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Yup, it will indeed extend your landing roll. Which is why you use it like flaps. When the field is made, push the blue knob in and the flaps down (the gear may need to be a bit earlier in a Cessna retract).

In a 182, the blue knob makes an easily noticeable difference in glide distance.
 
iamtheari said:
This was my thought, as well. If you feather the prop, it is not going to windmill for very long. That's the whole point of feathering it in the first place, to lose the drag of the windmilling prop. Once it stops windmilling, the oil pump stops turning and you lose pressure, which results in the prop return springs (or whatever mechanism is inside the magical prop hub) forcing the blades fine, which returns the drag. But then it may windmill again and build oil pressure back up. So...does it find a point of equilibrium? It sounds to me like, even if it did, you are trying to extract energy from the prop's drag through the air which means more drag than if you don't try to extract energy from it.

So that means to me that you likely get no benefit from pulling the prop lever back. And the only way to know for sure is going to be an experiment, which means the same airplane and pilot actually killing the engine in flight on multiple occasions. I call "not it."
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You are missing a key point: unless the engine/prop was specifically designed to feather (the vast majority of single engine pistons are not) you will never actually get the prop to feather and stop windmilling. It will continue to spin, but with less flat plate drag.
 
iamtheari said:
This was my thought, as well. If you feather the prop, it is not going to windmill for very long. That's the whole point of feathering it in the first place, to lose the drag of the windmilling prop. Once it stops windmilling, the oil pump stops turning and you lose pressure, which results in the prop return springs (or whatever mechanism is inside the magical prop hub) forcing the blades fine, which returns the drag. But then it may windmill again and build oil pressure back up. So...does it find a point of equilibrium? It sounds to me like, even if it did, you are trying to extract energy from the prop's drag through the air which means more drag than if you don't try to extract energy from it.

So that means to me that you likely get no benefit from pulling the prop lever back. And the only way to know for sure is going to be an experiment, which means the same airplane and pilot actually killing the engine in flight on multiple occasions. I call "not it."
Click to expand...

You can't "feather" a typical single enough to make the engine stop rotating at anything resembling best glide speed. Coarse pitch isn't very coarse.
 
I have an IO-540, MT governor and Hartzell prop. My blade pitch range is 11-31 degrees. The governor has its own pump that increases engine oil pressure 6X. On the bench, my prop required 45 psi to hit max pitch stop. My prop will easily move to coarse pitch, 900 rpm at max glide speed of 80 kias, 700 rpm at 54 kias(stall). There is about a 35% prop drag reduction, which can be noticeably felt when the blue knob is pulled out. My glide distance is about 2 nm/1000'. I practice simulated engine-out landings with blue knob forward and back, solo and gross wt. Heavy is best. Just some numbers from my experimental.
 
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