Early prop advance vs. late complex a/c

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TriGear28

Pre-takeoff checklist
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TriGear28
Moved this from another thread to a more appropriate one.

Ok, here's one to stir the pot perhaps.

a/c: Piper pa28-200 Arrow

An Instructor told another pilot friend of mine to only advance the prop full forward on short final, over the numbers, when committing to landing.

On an instrument approach in this a/c I have always completed the prop advance over the final approach fix, along with all of the other landing checklist items, excluding all the flaps. keeping in mind the auto retract speed of the gear.

The way I see it, if you advance early, the prop is already in place for a missed approach, in case one is needed, and it's one last thing to adjust last minute, complying with the philosophy of the 'stable approach' rule further. In other words, it seems to help achieve a stabilized glide slope early, and allow for a smooth missed. In VFR conditions, I have heard people argue that, in the event of an engine failure, the glide will be shallower. My opinion, in that case is, 'if you were on glide slope at approach speed, you most likely wouldn't have made the runway anyway.'

Should a flight instructor encourage early or late prop advancement, especially in trainer a/c?
 
I don't personally advance the prop on short final or before a missed approach nor have I ever been trained to. Keep in mind that if you go around or go missed the prop is only one part of the equation - you normally have to enrichen the mixture too, and that is something that you generally don't want to do prematurely. Particularly at high altitude airports. It's really no big deal to work the mixture, prop and throttle at the same time on a go around. For me anyway.
 
Mine goes full forward on the landing checklist, with the mixture. Usually that's before the gear goes down but not always. And I do it on the FAF like you, also. You don't really want to go missed or go around with the prop at cruise. You want to get out of that situation as quickly as possible.
 
I do not want to advance the prop control at a point where I still have enough power in to have the RPM increase when I do advance the prop control. On an ILS, I'll still have enough power in that if I push the prop control forward, I'm going to get max RPM. Poor form IMO, especially if you have unsuspecting passengers aboard ("what's that?").

If you need to go around, you can just cram all three power controls in at once in the vast majority of planes. But it's not THAT hard to push the prop control all the way in when you make the final power reduction prior to landing (not pulling it to zero in the flare, but when you slow down from approach speed to landing speed). That happens prior to pattern entry in the Mooney, prior to descending from pattern altitude in the 182 and DA40, and upon reaching approach minimums in all three.
 
I was taught prop full forward at FAF or midfield downwind but, if it ever was forgotten, I don't anticipate a problem for me to do it during a go around.
 
I don't advance the props until I'm going full power for the missed or go around, no need, no sense. Once you get below a certain power setting you'll be at fine pitch anyway, if I need more than 2200rpm worth of power I can add it then. It's only ever come up a couple of times in real life flying for me and presented as a non issue each time. Why make extra noise if you don't need the power? Be neighborhood noise friendly when you fly. Approach is a phase of flight where you can be pretty quiet with little effort. Personally I try to be back to 2450 before crossing airport property, and that's pretty much where I leave it until I land.
 
Our prop has a vernier so I just slowly twist it up, usually. Also usually wait until the power is back enough that it doesn't really change RPM much.

"Prop to go" from the checklist usually becomes slow mindless twisting with my right hand while I'm thinking about other stuff. Why stress parts, or destabilize everything? There's rarely any hurry.
 
flyingcheesehead said:
I do not want to advance the prop control at a point where I still have enough power in to have the RPM increase when I do advance the prop control. On an ILS, I'll still have enough power in that if I push the prop control forward, I'm going to get max RPM. Poor form IMO, especially if you have unsuspecting passengers aboard ("what's that?").
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This.

As long as you train it that way, delaying advancing the prop is a better way of doing things. Single pilot, I typically do it on short final when I am at low enough power in that I don't get a surge. Part of my short final gear check. In the DC-3 we don't advance the props until in the flare, but that is usually done by PNF. Part of your Go-Around technique in a complex airplane should always be to adjust the prop before adding throttle.
 
There is no one right way. Do what you feel works for you.

I do not advance the props. Mixture is left at lean (going rich because throttle is retarded - and carb heat is on) and the prop is left at cruise with some throttle carried all the way to the touch down to keep the cylinders warm.

IMO If you cannot handle the chore of advancing the prop and carb heat before full throttle during a balked landing, then you need to fly a simpler airplane.
But then, I am a grumpy old fart.
 
When I was training in the Mooney 201 the instructor had me push the prop forward before the FAF.

I feel it is unnecessary to have the prop swinging at full speed and making a bunch of racket. My technique now is to leave the prop @ 2300 rpm which is what I use for cruise descent. I get the gear and approach flaps out before the FAF, then when I hit the FAF I reduce power, and complete the landing checklist (mix rich, prop full forward yada yada).

When I make the initial power reduction the prop will spin down to about 2100 rpm which yields a nice descent rate for a glide slope. So when I push the prop control in, it stays at 2100 rpm.

There is nothing wrong with pushing the prop all the way in before the FAF. However I think one of the nice qualities of a constant speed prop is that it delivers a quieter smoother, more efficient ride than a fixed pitch prop if you know how to use it. Running along at 100 knots at full prop RPM is not quiet, smooth or efficient.
 
At low throttle like that, the prop is running at the fine pitch limit anyway. It simply isn't going to make any more RPM. As long as you get the prop to the firewall before the throttle, it doesn't matter how far ahead you do it.
 
I fly the Comanche at 2300 RPM pretty much all the time. I don't advance the prop until I see an RPM reduction on my approach. When that happens the prop control goes full forward. The only reason I do this is to be nice. We have enough people that complain about those "noisy little airplanes," no sense in ****ing more people off by making more noise.

For those you that put the prop full forward and make more noise, shame on you.
 
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MAKG1 said:
At low throttle like that, the prop is running at the fine pitch limit anyway. It simply isn't going to make any more RPM. As long as you get the prop to the firewall before the throttle, it doesn't matter how far ahead you do it.
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Yeah I mis-understood the original post. I think either way is fine. I push it forward after reducing power because as you stated its already at the fine pitch limit, and i'm already pushing buttons and stuff so why not. Its also on most every checklist i've seen.

The argument about making it glide better in case of an engine failure seems kinda dumb. As the OP noted if you are on the traditional 'stabilized' approach you're likely hosed anyway. Also with the flaps and gear out, you are so draggy what difference is the prop control turned back a few clicks gonna make? I think it needs to be pulled all the way out to make a noticeable difference. To get the thing to glide you need to reconfigure flaps and gear, and the prop control takes one second to pull out if you are already running a checklist
 
Several posters have touched on an important point...noise. If you want to call down the wrath of airport neighbors, push the prop full forward while still making power. Makes a nice bra-a-a-a-a-p sound.

I'm on the side of those who say do it late or don't do it at all, and I am not on board with the "in case of a go-around" crowd. If you are paying attention, you will see if anyone is waiting to enter the runway for takeoff or if there is a small boy with a bicycle (Okinawa) who just has to get across the runway while you are on final. If you won't touch down in the first one-third of the runway, that should be apparent on short final and you can do your mixture-prop-throttle thing in plenty of time.

Bob Gardner
 
I descend at 2100 RPM and pull MP back no more than 2" at a time. I try to only go below 15" on downwind once below 90 kts. After turning final prop/mixture go forward. During most of the time the engine runs, the cylinder rings are forced "down" against their lands, which also pushes them against the cylinder walls. If the RPM is very high, and the MP is very low, there is a large, negative pressure created in the combustion chamber during the intake stroke, due to the closed throttle plate and the piston trying hard to suck air in. This may lift the ring off its land during that stroke. The next stroke is the compression stroke, and while the pressure will be greatly reduced because not much air got in, it's still enough to push the ring back down again. This repetition may well cause the rings to "flutter," beating up and down within the land, and this may well cause damage.
 
RV10flyer said:
I descend at 2100 RPM and pull MP back no more than 2" at a time. I try to only go below 15" on downwind once below 90 kts. After turning final prop/mixture go forward. During most of the time the engine runs, the cylinder rings are forced "down" against their lands, which also pushes them against the cylinder walls. If the RPM is very high, and the MP is very low, there is a large, negative pressure created in the combustion chamber during the intake stroke, due to the closed throttle plate and the piston trying hard to suck air in. This may lift the ring off its land during that stroke. The next stroke is the compression stroke, and while the pressure will be greatly reduced because not much air got in, it's still enough to push the ring back down again. This repetition may well cause the rings to "flutter," beating up and down within the land, and this may well cause damage.
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Isn't about the only way to get that to happen is in a power-reduced dive?
 
EdFred said:
I fly the Comanche at 2300 RPM pretty much all the time. I don't advance the prop until I see an RPM reduction on my approach. When that happens the prop control goes full forward. The only reason I do this is to be nice. We have enough people that complain about those "noisy little airplanes," no sense in ****ing more people off by making more noise.

For those you that put the prop full forward and make more noise, shame on you.
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That's the way I do it: Once I've reduced power to the point that I'm below the governing range, e;i the RPM starts to come back, then I advance the prop control. If, on the other hand, I was shooting an ILS approach down to mins - and was expecting to have to miss, I would increase RPM sooner.
 
RV10flyer said:
I descend at 2100 RPM and pull MP back no more than 2" at a time. I try to only go below 15" on downwind once below 90 kts. After turning final prop/mixture go forward. During most of the time the engine runs, the cylinder rings are forced "down" against their lands, which also pushes them against the cylinder walls. If the RPM is very high, and the MP is very low, there is a large, negative pressure created in the combustion chamber during the intake stroke, due to the closed throttle plate and the piston trying hard to suck air in. This may lift the ring off its land during that stroke. The next stroke is the compression stroke, and while the pressure will be greatly reduced because not much air got in, it's still enough to push the ring back down again. This repetition may well cause the rings to "flutter," beating up and down within the land, and this may well cause damage.
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Huh? The rings oscillate on every stroke. The power stroke is A LOT larger a deviation from ambient than the intake stroke. So, you have it backwards. What's 10 PSI vacuum against thousands of PSI of pressure (full throttle) or hundreds (idle)? It doesn't make a dang bit of difference.

You make a lot more wear on the pistons just by variation in operating temperature. All air-cooled pistons fit loosely with large ring gaps. They have to.
 
RV10flyer said:
I descend at 2100 RPM and pull MP back no more than 2" at a time. I try to only go below 15" on downwind once below 90 kts. After turning final prop/mixture go forward. During most of the time the engine runs, the cylinder rings are forced "down" against their lands, which also pushes them against the cylinder walls. If the RPM is very high, and the MP is very low, there is a large, negative pressure created in the combustion chamber during the intake stroke, due to the closed throttle plate and the piston trying hard to suck air in. This may lift the ring off its land during that stroke. The next stroke is the compression stroke, and while the pressure will be greatly reduced because not much air got in, it's still enough to push the ring back down again. This repetition may well cause the rings to "flutter," beating up and down within the land, and this may well cause damage.
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nonsense, rings reverse every cycle. You can run an engine in power (engine turning flywheel) or motoring (flywheel turning engine) continuously by design. Moreso than that, you can fit an (truck or tractor) engine with a compression brake to provide even more resistance.

the OWT about motoring aircraft engines originated by a few harmonic speed points in a few geared engines. The protential damage in those cases was with the geartrain not with the engine.
 
Unless you're flying a geared engine, there's no real reason to worry about advancing the prop. You can use it for drag or not as you see fit. Frankly, on a go around, mashing it all to the wall generally responds pretty well.

Now with the geared engine we were always advised not to let the prop drive the engine which it doesn't normally see in any other phase of flight.
 
Count me in the "low noise is best" camp, hence prop goes up at low power setting. If you can hear the change, you did it too early.
 
EdFred said:
The only reason I do this is to be nice...no sense in ****ing more people off by making more noise..
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Who are you and what have you done with Ed? :D

Good point, though.
 
Ted DuPuis said:
Who are you and what have you done with Ed? :D

Good point, though.
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Oh, I changed out the cams and firing order on the Comanche. Now I've got the Harley rumble. Makes it a PITA to read the instruments though.
 
EdFred said:
Oh, I changed out the cams and firing order on the Comanche. Now I've got the Harley rumble. Makes it a PITA to read the instruments though.
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But you still have a muffler! Harleys are never loud enough unless they have zoomies.:mad2:

Changing out the firing order will either make no difference (waste spark) or will make for a dead engine....

Yeah, a 7000 RPM cam on a 2500 RPM engine ought to make for a nice Harley sound. And a POS....
 
EdFred said:
Oh, I changed out the cams and firing order on the Comanche. Now I've got the Harley rumble. Makes it a PITA to read the instruments though.
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Good idea, I should try that on the 310. Push my takeoff power from 2850 up to 5,000, add a GTSIO gearset.
 
JHW said:
nonsense, rings reverse every cycle. You can run an engine in power (engine turning flywheel) or motoring (flywheel turning engine) continuously by design. Moreso than that, you can fit an (truck or tractor) engine with a compression brake to provide even more resistance.

the OWT about motoring aircraft engines originated by a few harmonic speed points in a few geared engines. The protential damage in those cases was with the geartrain not with the engine.
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Since I paid $42,000 for a brand new engine from Lycoming and this is one of their recommendations, I start my descent far enough out to allow for slow cooling and also keep the prop loaded. It may not help, but it sure can't hurt it.
 
RV10flyer said:
Since I paid $42,000 for a brand new engine from Lycoming and this is one of their recommendations, I start my descent far enough out to allow for slow cooling and also keep the prop loaded. It may not help, but it sure can't hurt it.
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how about "keeping the prop loaded" during approach and landing ?
 
I don't have any complex experience so I'll ask the question, wouldn't finding out that the governor was misbehaving when you initiate the go around be bad and being in a position to know that early on prove beneficial?

Sent from my GT-P5113 using Tapatalk HD
 
+1 for the "out of governing range then prop" crowd. I like there to be no noticable change in engine operation for passengers.
 
airheadpenguin said:
I don't have any complex experience so I'll ask the question, wouldn't finding out that the governor was misbehaving when you initiate the go around be bad and being in a position to know that early on prove beneficial?

Sent from my GT-P5113 using Tapatalk HD
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We cycle prop before takeoff, so hopefully anything will show up then. I guess we could have a failure in governor causing prop pitch to increase which would really lug the engine down. I usually only pull rpm down from 1700 to 1400 or so. I know a guy who started with prop knob fully aft and then he wondered why rpm would not go above 1000 rpm no matter what the throttle position. I know my plane won't maintain level flight at 1000 rpm, so we would be up the creek.
 
RV10flyer said:
...... I know a guy who started with prop knob fully aft and then he wondered why rpm would not go above 1000 rpm no matter what the throttle position. I know my plane won't maintain level flight at 1000 rpm, so we would be up the creek.
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I don't know about "up the creek" but you will be "In the creek" anyway....:eek::D
 
airheadpenguin said:
I don't have any complex experience so I'll ask the question, wouldn't finding out that the governor was misbehaving when you initiate the go around be bad and being in a position to know that early on prove beneficial?

Sent from my GT-P5113 using Tapatalk HD
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if your prop governor fails it makes no difference where the control knob is
 
Only time I'll advance when still in power is when I'm in actual. No need to hit DH and have the situation more complicated. I had this happen to me once with clouds lower than reported in the morning when stuff was burning off.
 
Henning said:
I don't advance the props until I'm going full power for the missed or go around, no need, no sense. Once you get below a certain power setting you'll be at fine pitch anyway, if I need more than 2200rpm worth of power I can add it then. It's only ever come up a couple of times in real life flying for me and presented as a non issue each time. Why make extra noise if you don't need the power? Be neighborhood noise friendly when you fly. Approach is a phase of flight where you can be pretty quiet with little effort. Personally I try to be back to 2450 before crossing airport property, and that's pretty much where I leave it until I land.
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You are a great pilot Henning, some of us lessor pilots might find it easier to not have to worry about it in a go around as there is enough to do. :)
 
When ever you like, but my habit is when the speed falls off the governor to advance it. Just don't hang out in the red arc and you will not hurt the engine on an arrow.

Advantages to an early advance are less work later
A later advance may make transitioning to twins easier as often the props are left back untill short final.
 
Tony_Scarpelli said:
You are a great pilot Henning, some of us lessor pilots might find it easier to not have to worry about it in a go around as there is enough to do. :)
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Henning's method is actually a bit safer than advancing the prop and mixture during the approach IMO. If you get in the habit of pushing everything forward (with the possible exception of the mixture at high DA) any time you want full power (e.g. go-around, missed approach, takeoff, and climb) you won't end up with an improper control combination when the need for power is unexpected and/or you got distracted and didn't push the prop control up when you usually do.

I will admit that this is less practical with some airplanes where the controls aren't easy to operate together. In the Bonanza I used to own the mixture was on the opposite side of a pedestal (about 10" from the throttle) so it did take some extra effort and time to get all three controls to the full power setting. With such an airplane it might indeed make sense to "prepare" for a go-around (VMC or IMC) at some point on final once the throttle is closed enough that the RPM won't increase when you push the control forward.
 
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