Prop lever (am I doing something wrong)

[bradcarr]

Ok so My prop lever lives at the top.  Obviously, it gets moved during runup.  And i do move it the .00001 inches it seems to take to set a 2500 or 2400 rpm setting.  Then during my 2-hour XC i repeatedly think to myself.... you know that poor blue lever never gets any love.  I get to move the throttle all over as I come in to land.  I get to adjust that red gas money lever off and on throughout the flight.  But poor old blue guy just gets moved that mysterious .00001 inches.  Is this just how it is?  Or does everyone else have power setting or something that causes them to get to play more with old Bluie?

For reference I spend most of my time between 7500 and 9500 in the flat lands of the south.

Just an observation i noticed.  Plane is flying great.  My speed, fuel burn and engine heat all seem to be doing what they should, so I just thought I'd ask peoples thoughts.

[TheAv8r]

The blue lever should be touched at a minimum, 2 times while inflight:

1. When setting cruise power, moving the RPM to the desired RPM for cruise. 
2. Prior to landing, set at max RPM to have full available takeoff power in the event of a go-around. 

Outside of those 2 times, it's pretty normal not to need to touch it again .

[Hank]

@bradcarr, I move the prop lever during engine runup prior to takeoff, then back to Max, where it stays until I level off. At your altitudes, I run 2500, which is about an inch back. At lower altitudes, I will cruise at 2300 or 2400; I fly many approaches at 2300 due to low altitudes. 

Looks like this at 2500:

[PT20J]

Are you saying that the control only moves a hair width from 2700 rpm to 2500 rpm? If so that’s not correct.

[bradcarr]

1 hour ago, PT20J said:

Are you saying that the control only moves a hair width from 2700 rpm to 2500 rpm? If so that’s not correct.

I guess part of me is exaggerating based on how much I get to move the others.  And I'd say I probably look a lot like Mr Hank on his picture at cruise based on what I can remember since it's been 4 days since I've flown.  But i certainly wouldn't say I'm moving the prop lever 1/4 of the way to get to 2400 if that is what you're asking.

[Vance Harral]

If you have the quadrant style throttle like in the picture above, and if you also have the fairly tight restricted RPM range (green arc 2350-2700), then yes, almost the entire normal operating range of the propeller is traversed by small movements at the top of the propeller control lever range.  We cruise at 2500 RPM, and I'd estimate the lever travel between there and 2700 RPM to be an inch or less.  Ours actually used to be even more sensitive with the old Woodward prop governor.  After replacing that with a McCauley governor, it's a little easier to control, but still pretty sensitive.

[PT20J]

40 minutes ago, bradcarr said:

I guess part of me is exaggerating based on how much I get to move the others.  And I'd say I probably look a lot like Mr Hank on his picture at cruise based on what I can remember since it's been 4 days since I've flown.  But i certainly wouldn't say I'm moving the prop lever 1/4 of the way to get to 2400 if that is what you're asking.

As long as you can make redline rpm just before liftoff and can adjust the prop to 2400-2600 rpm for cruise, then everything is fine. Most use the cruise rpm that is smoothest and will generate desired power when combined with available manifold pressure. Personally, I take off and climb at 2700 rpm and cruise at 2500 rpm unless above 10,000’ when I use 2600 rpm to get more power from the reduced manifold pressure available at full throttle. 

[Flyler]

4 hours ago, bradcarr said:

Ok so My prop lever lives at the top.  Obviously, it gets moved during runup.  And i do move it the .00001 inches it seems to take to set a 2500 or 2400 rpm setting.  Then during my 2-hour XC i repeatedly think to myself.... you know that poor blue lever never gets any love.  I get to move the throttle all over as I come in to land.  I get to adjust that red gas money lever off and on throughout the flight.  But poor old blue guy just gets moved that mysterious .00001 inches.  Is this just how it is?  Or does everyone else have power setting or something that causes them to get to play more with old Bluie?

For reference I spend most of my time between 7500 and 9500 in the flat lands of the south.

Just an observation i noticed.  Plane is flying great.  My speed, fuel burn and engine heat all seem to be doing what they should, so I just thought I'd ask peoples thoughts.

The first "blue lever" I used was an M20F with a throttle quadrant and I was absolutely mystified as to why it was so incredibly sensitive.  Why would the lever have the same range as the throttle but only be used at the top 95-100% of its range in practice??  Well, that's just how it is.  My M20J has push/pull controls, which makes the sensitivity a bit less obvious, as you have the nice vernier action.  I asked my instructor/A&P about this and he reckons its just a fact of life with the range of the linkage, something like that.  They are supposed to be that way.

[bradcarr]

39 minutes ago, Flyler said:

The first "blue lever" I used was an M20F with a throttle quadrant and I was absolutely mystified as to why it was so incredibly sensitive.  Why would the lever have the same range as the throttle but only be used at the top 95-100% of its range in practice??  Well, that's just how it is.  My M20J has push/pull controls, which makes the sensitivity a bit less obvious, as you have the nice vernier action.  I asked my instructor/A&P about this and he reckons its just a fact of life with the range of the linkage, something like that.  They are supposed to be that way.

LOL. mine is a 75 M20F.  And your description is really why I asked.  I mean I know its working at intended, as I can redline it in a climb and pull it back.  But it was just kind of funny to me that so little is required to moved it after takeoff to climb.  May be silly but it will probably continue to make me chuckle a bit every time I'm up.  May need to make a Mooney t-shirt with Blue Lever Deserves Love Too on it.....

[PT20J]

The prop control has more range of movement than necessary for normal operation to allow full control of the blade angle between the high and low pitch stops. Normally, the control is fairly far advanced because we operate at an rpm that is within a few hundred rpm of redline. But, in the event of an engine failure, pulling the prop control all the way back will drive the blades to the high pitch stop greatly reducing drag and increasing the glide distance. 

[Vance Harral]

@PT20J beat me to it, but I was writing that If you want to feel like you're getting your full money's worth out of the blue knob, try playing with it in an idling glide.  Specifically, climb high enough to practice an engine out glide, set normal power, then pull the throttle to idle, establish best glide speed, and observe your glide ratio with the prop windmilling at your normal cruise blue knob setting.  Then pull that thing all the way back and take note of the difference in descent rate and glide ratio.  As Skip says, it's a big enough difference to notice.

Mostly you shouldn't need this trick.  But it's one to keep up your sleeve if the fickle fates align to present you with an engine out (but not seized) scenario at high altitude.  Or if you need just a few more feet of glide distance to make your Commercial Pilot Power-Off 180 Landing work out to ACS standards.

[hazek]

25 minutes ago, PT20J said:

But, in the event of an engine failure, pulling the prop control all the way back will drive the blades to the high pitch stop greatly reducing drag and increasing the glide distance. 

I'm not trying to dispute this at all but I'm very curious why my Bravo POH has no mention of this in section 3. Anyone have a clue about this?

[Will.iam]

2 hours ago, hazek said:

I'm not trying to dispute this at all but I'm very curious why my Bravo POH has no mention of this in section 3. Anyone have a clue about this?

My m20k poh does not have it either but that doesn’t mean it doesn’t work. I’m n fact it works very well more effective than speed brakes and more variable than gear. 

[Hank]

3 hours ago, hazek said:

I'm not trying to dispute this at all but I'm very curious why my Bravo POH has no mention of this in section 3. Anyone have a clue about this?

It's not in my Owners Manual, either. But it has been mentioned by several CFI / CFII who've flown with me.

Try it, you'll be surprised by its effectiveness. 

My first Mooney instructor briefed me while practicing descending to pattern altitude that pushing the prop forward, my 3-blade Hartzell makes a great speed brake; similarly, pulling the prop back is like taking your foot off of the brakes.

[Slick Nick]

5 hours ago, Vance Harral said:

@PT20J beat me to it, but I was writing that If you want to feel like you're getting your full money's worth out of the blue knob, try playing with it in an idling glide.  Specifically, climb high enough to practice an engine out glide, set normal power, then pull the throttle to idle, establish best glide speed, and observe your glide ratio with the prop windmilling at your normal cruise blue knob setting.  Then pull that thing all the way back and take note of the difference in descent rate and glide ratio.  As Skip says, it's a big enough difference to notice.

Mostly you shouldn't need this trick.  But it's one to keep up your sleeve if the fickle fates align to present you with an engine out (but not seized) scenario at high altitude.  Or if you need just a few more feet of glide distance to make your Commercial Pilot Power-Off 180 Landing work out to ACS standards.

Is this okay to do without causing any undue stress to the engine?

[Hank]

22 minutes ago, Slick Nick said:

Is this okay to do without causing any undue stress to the engine?

Sure. Don't you occasionally practice engine out landings? Once the throttle is at idle, pulling back the prop actually reduces how much the prop is driving the engine 

[Jackk]

Just now, Hank said:

Sure. Don't you occasionally practice engine out landings? Once the throttle is at idle, pulling back the prop actually reduces how much the prop is driving the engine 

If your engine was actually out do you still think that trick would work?

[Justin Schmidt]

1 hour ago, Jackk said:

If your engine was actually out do you still think that trick would work?

Depends on the governor failure mode

[hazek]

2 hours ago, Justin Schmidt said:

Depends on the governor failure mode

Doesn't it depend on oil pressure? If you have none you can't go high pitch since there's a spring into the opposite direction. @Hank and @Will.iam, maybe that's why the POH doesn't mention it, perhaps with engine failure, even if the engine is windmilling, there's not enough oil pressure to overcome the spring?

Also, speaking of weird prop level behavior, can someone shed light on why in a ground runup for me it's the opposite what the OP describes. If I use the vernier to reduce RPM I can wind out the lever very far before the RPM drops. Is this normal? And actually, I was at a maintenance shop last year where the guy told me it should be checked like that, but I forgot his explanation why.

[Jackk]

8 hours ago, Justin Schmidt said:

Depends on the governor failure mode

 My understanding is, unless you got a STC/337 to install something out of a multi engine piston plane that’s built to feather failed, it’s going to go fine pitch (prop forward)  if the oil pressure tanks a dump.

 

 When I was a new CFI I would teach that same trick for some of the CPL maneuvers, I then learned the single engine piston failure mode of the prop and stopped teaching that, I didn’t want to ingrain my students to use a tool that they most likely wouldn’t have in a high stakes moment when they might need it. 

Edited January 9 by Jackk

[N201MKTurbo]

If the engine is windmilling, it should work as long as it still has oil. 
 

You have nothing to lose by pulling the prop back. If it works, great! If it doesn’t , oh well, you tried.

[Vance Harral]

11 hours ago, Slick Nick said:

Is this okay to do without causing any undue stress to the engine?

Sigh.  I guess I can sorta sympathize with these kinds of questions when the cost of an engine overhaul is $50K for a simple Lycoming 4-cylinder and double that for a high-end Mooney.  But there's a lot of bad risk management information circulating out there.

Data point: the case on our IO-360-A1A was last split in 1991.  We bought it in 2004, now on 22nd year of operation since purchase, with 2700+ hours and 30+ years since that 1991 case split.  In our partnership we have never, and I mean never, spent one minute worrying about the prop driving the engine or shock cooling.  Every pilot in the partnership has performed  "stressful" commercial maneuvers on the regular: not just power-off 180s, but full-power Chandelles followed immediately by steep spirals at idle.  We don't pre-heat unless it's below 20 degrees, and when we do we just use a simple space heater and blanket.  We don't tape off the oil cooler in the winter or constantly fiddle with the cowl flaps to achieve "optimum" cylinder head and oil temps.  We don't agonize over oil change intervals or what type of oil to use, yadda, yadda, yadda.  The worst incidents we've had throughout these decades of operation involve oil leaks in the engine and prop governor, and I think it's essentially guaranteed those are a result of calendar time (seals and hoses drying out) rather than operating technique.

In the mean time, as an instructor at the local flight school, I watch a fleet of 4-cylinder Lycomings get abused on the daily: cold engine starts on the ramp by inexperienced students with the engine immediately going to 1500+ RPM.  CHTs well in excess of 400 degrees in the summer followed immediately by idle-power engine-out training.  Engines on the twin being cycled from full power to idle (or shutdown altogether) over and over and over again during engine failure training and Vmc demos, and so on.  None of these airplanes are falling out of the sky, and all of them are making TBO (or in some cases well beyond).

My point is not that we're right to operate our engine "abusively" and others are wrong to be more cautious.  I'm open to the idea that on a statistical basis, careful operators might get a few more hours out of an engine before it starts making metal or the governor fails or whatever - particularly on airplanes that are not flown frequently.  But it just drives me nuts that every time someone talks about training techniques that have real, tangible benefit - including being ready an actual engine failure - the engine worrywarts show up and imply that you'll destroy your engine if you don't treat it like a Faberge Egg.  In my flight instruction work, it's not uncommon for me to come in contact with owners who simply don't want apply sufficient power in a stall recovery, won't practice engine out scenarios, etc., for fear of damaging that precious engine.  These folks are not doing themselves any favors, and I have to have awkward conversations with them about their misplaced fears.

So please, my brothers and sisters of the skies.  For the love of all that is holy.  Stop worrying so much about "abusing" your engine.  A lot of you are overly focused on tiny, almost meaningless risks, at the expense of actually operating and fully understanding your power plants.

[Vance Harral]

1 hour ago, Jackk said:

My understanding is, unless you got a STC/337 to install something out of a multi engine piston plane that’s built to feather failed, it’s going to go fine pitch (prop forward)  if the oil pressure tanks a dump.

Correct, but a complete loss of oil pressure (likely leading to the engine seizing) is not the most common engine failure mechanism.  If the engine is windmilling and you've got any oil at all in the system, the governor is going to be at least somewhat effective in moving the prop toward low pitch.  This is especially true in the most common engine failure mode - running out of gas.

Having said that, it's somewhat unlikely the glide ratio improvement from moving the prop to coarse pitch is going to be the difference between a successful and unsuccessful engine-out scenario.  Survivability is almost entirely governed by your ability to pick a suitable landing spot within a very conservative gliding distance, and maneuver the airplane to arrive in that spot at minimum energy using a combination of flight path, drag devices, slips, etc.  You won't be able to do that unless you practice it at least occasionally.  And you won't practice it if you're afraid of damaging the engine doing so, see my rant above.

[Will.iam]

I will repeat it again based on actual experience of doing it not hypothetically guessing, that pulling the prop level full back will increase your glide distance by a very noticeable amount if your engine failure is not loss of oil. At one point i was trying to get the propeller to stop completely as to test the “theory” that a stopped propeller is more glide efficient than a propeller that is windmilling. Unfortunately to get my prop stopped took me flying so slow and below L/D max that i was losing more glide distance from dropping out of the air than the stopped propeller was offsetting. The moment i lowered the nose the slightest amount to speed up toward L/D max the propeller started turning again and started to speed up but then you see the rpm’s level off and then drop back down as the oil pressure was built up enough to change the pitch of the blades. Suffice to say the mccauley prop governor takes very little oil pressure to effectively drive the prop to low rpms. Most likely by mandate or design. 

[PT20J]

1 hour ago, Will.iam said:

Suffice to say the mccauley prop governor takes very little oil pressure to effectively drive the prop to low rpms. Most likely by mandate or design. 

The governor has an internal pump to create the higher pressure necessary to control the prop, so as long as the engine is rotating and there is oil available to the governor, it should be able to control the prop.