I was checking out in a Civil Air Patrol 182T the other day and the
check airman pulled the power on me. No big deal, but then he
demonstrated how the glide improved when the propeller was pulled to
low RPM. No one had ever showed that to me before.

Question is:

In retrospect it seems obvious that there will be less resistance when
the prop is closer to a feathered position. Buy why don't I see this
as part of emergency checklists for airplanes with constant speed
props? What am I missing here?

It, does work, but most people don't know it or teach it. The improvement
in glide isn't great, however.

Rod

Lots of planes include this. The Bonaza I used to teach in gave two
best glide speeds, one for prop forward, one for prop back. My Mooney
also recommends prop back.

Its interesting that he did this in the 182T though. In our wing we
require pilots to be 182 current (annual form 5) before checking out in
the 182T. The 182T checkride is just about the glass cockpit and
autopilot usage.

-Robert, CAP check pilot

Mitty wrote:
> I was checking out in a Civil Air Patrol 182T the other day and the
> check airman pulled the power on me. No big deal, but then he
> demonstrated how the glide improved when the propeller was pulled to
> low RPM. No one had ever showed that to me before.
>
> Question is:
>
> In retrospect it seems obvious that there will be less resistance when
> the prop is closer to a feathered position. Buy why don't I see this
> as part of emergency checklists for airplanes with constant speed
> props? What am I missing here?

It's a technique I was taught during my commercial license training as
a way of adjusting drag when doing the "180-degree power-off precision
landing".

My guess is that it's not included in emergency checklists beacuse
once the engine stops, you loose oil pressure, and the propellor will
go to the fine-pitch position anyway on a single-engine plane.
It's not something you can rely on in an emergency.

Tim.

On Sat, 15 Jul 2006 14:06:18 -0500, Mitty > wrote:

>I was checking out in a Civil Air Patrol 182T the other day and the
>check airman pulled the power on me. No big deal, but then he
>demonstrated how the glide improved when the propeller was pulled to
>low RPM. No one had ever showed that to me before.
>
>Question is:
>
>In retrospect it seems obvious that there will be less resistance when
>the prop is closer to a feathered position. Buy why don't I see this
>as part of emergency checklists for airplanes with constant speed
>props? What am I missing here?

It was a conventional panel "T." The glass is next.

On 7/15/2006 3:27 PM, Robert M. Gary wrote the following:
> Lots of planes include this. The Bonaza I used to teach in gave two
> best glide speeds, one for prop forward, one for prop back. My Mooney
> also recommends prop back.
>
> Its interesting that he did this in the 182T though. In our wing we
> require pilots to be 182 current (annual form 5) before checking out in
> the 182T. The 182T checkride is just about the glass cockpit and
> autopilot usage.
>
> -Robert, CAP check pilot
>
> Mitty wrote:
>> I was checking out in a Civil Air Patrol 182T the other day and the
>> check airman pulled the power on me. No big deal, but then he
>> demonstrated how the glide improved when the propeller was pulled to
>> low RPM. No one had ever showed that to me before.
>>
>> Question is:
>>
>> In retrospect it seems obvious that there will be less resistance when
>> the prop is closer to a feathered position. Buy why don't I see this
>> as part of emergency checklists for airplanes with constant speed
>> props? What am I missing here?
>

Mitty > wrote:

> Buy why don't I see this
> as part of emergency checklists for airplanes with constant speed
> props? What am I missing here?

My '73 Bonanza V35 has "pull the prop" (or word to that effect) as part of
the delivered emergency checklist.


--
Peter

It works and should be part of a complex check-out. You can
also push the prop back to high rpm and slow down to get
into a short field.


--
James H. Macklin
ATP,CFI,A&P

"Mitty" > wrote in message
...
|I was checking out in a Civil Air Patrol 182T the other day
and the
| check airman pulled the power on me. No big deal, but
then he
| demonstrated how the glide improved when the propeller was
pulled to
| low RPM. No one had ever showed that to me before.
|
| Question is:
|
| In retrospect it seems obvious that there will be less
resistance when
| the prop is closer to a feathered position. Buy why don't
I see this
| as part of emergency checklists for airplanes with
constant speed
| props? What am I missing here?

If the engine is turning, it has oil pressure.


To get maximum glide, a stopped prop has less drag, but most
instructors do not recommend slowing down enough to stop the
prop,on compression.


--
James H. Macklin
ATP,CFI,A&P

"Tim Auckland" > wrote in message
...
| It's a technique I was taught during my commercial license
training as
| a way of adjusting drag when doing the "180-degree
power-off precision
| landing".
|
| My guess is that it's not included in emergency checklists
beacuse
| once the engine stops, you loose oil pressure, and the
propellor will
| go to the fine-pitch position anyway on a single-engine
plane.
| It's not something you can rely on in an emergency.
|
| Tim.
|
| On Sat, 15 Jul 2006 14:06:18 -0500, Mitty
> wrote:
|
| >I was checking out in a Civil Air Patrol 182T the other
day and the
| >check airman pulled the power on me. No big deal, but
then he
| >demonstrated how the glide improved when the propeller
was pulled to
| >low RPM. No one had ever showed that to me before.
| >
| >Question is:
| >
| >In retrospect it seems obvious that there will be less
resistance when
| >the prop is closer to a feathered position. Buy why
don't I see this
| >as part of emergency checklists for airplanes with
constant speed
| >props? What am I missing here?
|

"Jim Macklin" > wrote:
> If the engine is turning, it has oil pressure.

Only if it has oil.

Still, I teach pulling the prop all the way back. It may work, it may not,
but it sure can't hurt.

On 7/15/2006 6:28 PM, Roy Smith wrote the following:
> "Jim Macklin" > wrote:
>> If the engine is turning, it has oil pressure.
>
> Only if it has oil.
>
> Still, I teach pulling the prop all the way back. It may work, it may not,
> but it sure can't hurt.

Makes sense to me.

In article <TKdug.77158$ZW3.34119@dukeread04>,
"Jim Macklin" > wrote:

> If the engine is turning, it has oil pressure.

Yes, but is there not a minimum RPM below which the governor has no
effect?

That's true. Also, knowing that the prop and governor are
using engine oil, apply that if you have a zero engine oil
pressure indication, if the prop work-so is the engine oil
pump and there is some oil pressure and volume. Still, a
precautionary landing is advised, but don't panic and cause
more problems with a shutdown or off airport landing.

In a single-engine airplane, the prop will go to low pitch,
high rpm and operate as a fixed pitch if you do not have
pressurized oil from the governor and it won't be supplied
unless the engine oil pump is working. In a multiengine
airplane, the first indicator of a failure may be the
affected prop feathering.


If my aunt had been born with different plumbing, she'd have
been my uncle.


--
James H. Macklin
ATP,CFI,A&P

"Roy Smith" > wrote in message
...
| "Jim Macklin" >
wrote:
| > If the engine is turning, it has oil pressure.
|
| Only if it has oil.
|
| Still, I teach pulling the prop all the way back. It may
work, it may not,
| but it sure can't hurt.

When the prop is on the high or low pitch stops, which
should be indicated by the green arc on the tach and with
power applied. With a single engine, doing a run-up at say
2000 rpm, the governor can reduce rpm to perhaps 1700 rpm.
The prop control is full forward and the prop is on the low
pitch stop as you begin the run-up. Pulling the prop
control back moves the prop towards the high pitch stops.
Most pilots seem to think cycling the prop is just to
circulate fresh warm oil. Give the system a moment to have
the rpm stabilize to see what is happening. On a
multiengine run-up, doing the feather check, pull the prop
back to the feather dent and the prop should stabilize at
the bottom of the green arc, probably about 2000 rpm on a
piston engine. Let it run there a moment to see that it
does get to the full governed range and does not feather
until you pull the control through the detent, then it
should begin to feather. I've seen many airplane misrigged,
that would feather before the detent or would not reach the
minimum governor range even though a typical quick test
would be seen as "normal" by many rated pilots.


--
James H. Macklin
ATP,CFI,A&P

"john smith" > wrote in message
...
| In article <TKdug.77158$ZW3.34119@dukeread04>,
| "Jim Macklin" >
wrote:
|
| > If the engine is turning, it has oil pressure.
|
| Yes, but is there not a minimum RPM below which the
governor has no
| effect?

On Sat, 15 Jul 2006 14:55:09 -0600, Tim Auckland > wrote:

>It's a technique I was taught during my commercial license training as
>a way of adjusting drag when doing the "180-degree power-off precision
>landing".
>
>My guess is that it's not included in emergency checklists beacuse
>once the engine stops, you loose oil pressure, and the propellor will
>go to the fine-pitch position anyway on a single-engine plane.

Which makes virtually no difference from the coarse setting to stopped
as far as drag.

>It's not something you can rely on in an emergency.

Yes it is if the prop is wind milling. If the prop stops it'll have
about the same drag or maybe a bit less than it did in corase pitch
while wind milling.

It's one of those; nothing to lose and a bit to gain by doing.


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
Current return address does not work...have to fix it.

>
>Tim.
>
>On Sat, 15 Jul 2006 14:06:18 -0500, Mitty > wrote:
>
>>I was checking out in a Civil Air Patrol 182T the other day and the
>>check airman pulled the power on me. No big deal, but then he
>>demonstrated how the glide improved when the propeller was pulled to
>>low RPM. No one had ever showed that to me before.
>>
>>Question is:
>>
>>In retrospect it seems obvious that there will be less resistance when
>>the prop is closer to a feathered position. Buy why don't I see this
>>as part of emergency checklists for airplanes with constant speed
>>props? What am I missing here?
Roger

john smith wrote:
> In article <TKdug.77158$ZW3.34119@dukeread04>,
> "Jim Macklin" > wrote:
>
>> If the engine is turning, it has oil pressure.
>
> Yes, but is there not a minimum RPM below which the governor has no
> effect?

Yeah, but at best glide (provided the engine hasn't siezed up) it
will windmill way above this point at best-glide speeds.

Jim Macklin > wrote:

> Pulling the prop
> control back moves the prop towards the high pitch stops.
> Most pilots seem to think cycling the prop is just to
> circulate fresh warm oil. Give the system a moment to have
> the rpm stabilize to see what is happening.

Leave it there a moment? Hmmm, when I transitioned to the Bonanza, my
first constant speed prop aircraft, I was told by the very experienced CFI
not to let the RPMS drop too much during this pre-takeoff item or it would
place a high load on the engine (I believe his analogy was like shifting a
car into 4th gear while driving at 25 miles per hour).

Not true?

--
Peter

In article >,
"Peter R." > wrote:


>
> Leave it there a moment? Hmmm, when I transitioned to the Bonanza, my
> first constant speed prop aircraft, I was told by the very experienced CFI
> not to let the RPMS drop too much during this pre-takeoff item or it would
> place a high load on the engine (I believe his analogy was like shifting a
> car into 4th gear while driving at 25 miles per hour).
>

At the power setting for runup I can't see it being a problem.

On the radials on the B-17 and B-24 part of the check was to bring the
prop controls to the low RPM position to check the low RPM pitch stop.
We wanted to see the RPM hold at 1200.

If the MAP is around 20 inches, you can run the prop back to
minimum rpm without having any problem. On a multiengine
aircraft, you can cruise at minimum governed rpm and high
MAP [within the limits shown in the POH] without harm to the
engine. You don't do a feather check or a prop check at
full throttle at sea level. I'm not talking about slamming
the control full range, but taking a few seconds so dynamic
forces are not excessive. I don't have a Bonanza manual
handy today, but the P58 Baron has a tach range of
2000-2700, run-up at 2000 rpm [less than full throttle] and
the feather check at 1500 rpm.

The multiengine aircraft can run at the 2000 rpm setting
indefinitely, as long as the limitations on the MAP are not
exceeded. The P58 Baron shows a recommended cruise setting
of 30 inches and 2200 rpm. At 2000 rpm the engine won't
be as smooth. In the limitations or cruise section of the
POH, there is usually a chart that shows permissible rpm vs.
MAP for continuous operation.

You don't need to rush these tests and you don't do them at
full power.


--
James H. Macklin
ATP,CFI,A&P

"Peter R." > wrote in message
...
| Jim Macklin > wrote:
|
| > Pulling the prop
| > control back moves the prop towards the high pitch
stops.
| > Most pilots seem to think cycling the prop is just to
| > circulate fresh warm oil. Give the system a moment to
have
| > the rpm stabilize to see what is happening.
|
| Leave it there a moment? Hmmm, when I transitioned to the
Bonanza, my
| first constant speed prop aircraft, I was told by the
very experienced CFI
| not to let the RPMS drop too much during this pre-takeoff
item or it would
| place a high load on the engine (I believe his analogy was
like shifting a
| car into 4th gear while driving at 25 miles per hour).
|
| Not true?
|
| --
| Peter

Peter R. wrote:

> Leave it there a moment? Hmmm, when I transitioned to the Bonanza, my
> first constant speed prop aircraft, I was told by the very experienced CFI
> not to let the RPMS drop too much during this pre-takeoff item or it would
> place a high load on the engine (I believe his analogy was like shifting a
> car into 4th gear while driving at 25 miles per hour).
>
> Not true?
>
There's no advantage to letting it hang at low RPM's. What you
DO want to do is make sure it comes all the way back up to the
same "initial" RPM you started the exercise with.

Right on. In the big radials, the feathering was done with
a feathering button that powered a feather pump, so there
was no issue of feathering with the prop control. But in
the light twin, the prop lever control rpm and when it is
moved through a detent, the governor dumps the oil and the
prop feathers. But you can set the engine to an idle of
about 1000-1200 rpm and then feather the engine and let the
prop go all the way. But at idle the engine won't feather
because the stops will prevent the prop from feathering.
You do a feather check at 1500 rpm because that assures the
stops are retracted with enough rpm to allow the blades to
get into the feather range. You can run on the detent ass
long as you wish, but unless you want the engine to shake,
shudder and need to have the prop unfeather during the start
attempt, don't let the rpm drop below 1,000 rpm during the
feather test. If you have unfeathering accumulators it is a
one shot deal to get started...with the prop control still
in feather, prime and engage then starter, when you start to
get a little oil pressure and the engine is firing, move the
prop control full forward and hope you have enough oil
pressure from the governor to move the prop blades out of
feather. This is an emergency technique, much better to
have a mechanic use blade boards to manual turn the blades
out of feather.


--
James H. Macklin
ATP,CFI,A&P

"Dale" > wrote in message
...
| In article
>,
| "Peter R." > wrote:
|
|
| >
| > Leave it there a moment? Hmmm, when I transitioned to
the Bonanza, my
| > first constant speed prop aircraft, I was told by the
very experienced CFI
| > not to let the RPMS drop too much during this
pre-takeoff item or it would
| > place a high load on the engine (I believe his analogy
was like shifting a
| > car into 4th gear while driving at 25 miles per hour).
| >
|
| At the power setting for runup I can't see it being a
problem.
|
| On the radials on the B-17 and B-24 part of the check was
to bring the
| prop controls to the low RPM position to check the low RPM
pitch stop.
| We wanted to see the RPM hold at 1200.

In article >,
"Peter R." > wrote:

> Jim Macklin > wrote:
>
> > Pulling the prop
> > control back moves the prop towards the high pitch stops.
> > Most pilots seem to think cycling the prop is just to
> > circulate fresh warm oil. Give the system a moment to have
> > the rpm stabilize to see what is happening.
>
> Leave it there a moment? Hmmm, when I transitioned to the Bonanza, my
> first constant speed prop aircraft, I was told by the very experienced CFI
> not to let the RPMS drop too much during this pre-takeoff item or it would
> place a high load on the engine (I believe his analogy was like shifting a
> car into 4th gear while driving at 25 miles per hour).
> Not true?

I cannot remember where I read it (sometime in the past year), not to
allow the rpm to drop more than 500 rpm during the prop check at runup
rpm.

In article
>,
john smith > wrote:

> In article >,
> "Peter R." > wrote:
>
> > Jim Macklin > wrote:
> >
> > > Pulling the prop
> > > control back moves the prop towards the high pitch stops.
> > > Most pilots seem to think cycling the prop is just to
> > > circulate fresh warm oil. Give the system a moment to have
> > > the rpm stabilize to see what is happening.
> >
> > Leave it there a moment? Hmmm, when I transitioned to the Bonanza, my
> > first constant speed prop aircraft, I was told by the very experienced CFI
> > not to let the RPMS drop too much during this pre-takeoff item or it would
> > place a high load on the engine (I believe his analogy was like shifting a
> > car into 4th gear while driving at 25 miles per hour).
> > Not true?
>
> I cannot remember where I read it (sometime in the past year), not to
> allow the rpm to drop more than 500 rpm during the prop check at runup
> rpm.

Go to http://www.mattituck.com/articles/goodhabt.htm and scroll down to
"Keep Propeller Cycling To A Minimum".

If there is limitation published for your airplane (POH),
certainly follow that, but the old wives' tale about
over-square operation is part of this issue. With enough
power applied, a CS prop will reach red-line rpm on the
ground [a fixed pitch won't, it has a published minimum rpm
with a particular prop]. You reach the rpm at less than
full throttle with a CS prop, which is on the low pitch
stop. Pull the rpm back causes the governor to send oil to
the hub which takes the prop off the low pitch stops. This
at about half throttle.
You can cruise at 120 kts {just a number} and minimum rpm at
say 2000 because air loads are reduced and you're using more
power. The rpm will decrease on a ground run because there
isn't enough power to keep the rpm up and you will get to
the high pitch stop.
In any case, you should be checking more than a connection
between the prop control and the prop, does the governor
govern? On a multiengine, will it run at the power rpm as
shown on the green arc and be stable? On a single-engine,
can you set some rpm below the initial run-up and does that
run at a constant speed.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"john smith" > wrote in message
...
| In article
>,
| "Peter R." > wrote:
|
| > Jim Macklin >
wrote:
| >
| > > Pulling the prop
| > > control back moves the prop towards the high pitch
stops.
| > > Most pilots seem to think cycling the prop is just to
| > > circulate fresh warm oil. Give the system a moment to
have
| > > the rpm stabilize to see what is happening.
| >
| > Leave it there a moment? Hmmm, when I transitioned to
the Bonanza, my
| > first constant speed prop aircraft, I was told by the
very experienced CFI
| > not to let the RPMS drop too much during this
pre-takeoff item or it would
| > place a high load on the engine (I believe his analogy
was like shifting a
| > car into 4th gear while driving at 25 miles per hour).
| > Not true?
|
| I cannot remember where I read it (sometime in the past
year), not to
| allow the rpm to drop more than 500 rpm during the prop
check at runup
| rpm.

"rod" wrote:

> It, does work, but most people don't know it or teach it. The improvement
> in glide isn't great, however.

It's over 50 FPM less sink in my airplane.

That may not seem like much, but if you only need a few more feet to glide
over some trees, it will seem like a whole lot.

--
Dan
C172RG at BFM

"john smith" > wrote in message
...
> In article <TKdug.77158$ZW3.34119@dukeread04>,
> "Jim Macklin" > wrote:
>
>> If the engine is turning, it has oil pressure.
>
> Yes, but is there not a minimum RPM below which the governor has no
> effect?

There is indeed. In my experience, cycling the prop on a windmilling engine
has no effect. I'm talking about a constant speed prop on a single engine
aircraft, in this case a Mooney 201. Windmill RPM was about 800, and no
amount of pulling on the prop control would change that RPM. Obviously, if
the RPM doesn't change, the prop pitch didn't change, and the glide is not
affected.

Jim and I have 'round on this one before, but I stand by my observations.

Al G

Al wrote:

> There is indeed. In my experience, cycling the prop on a windmilling engine
> has no effect. I'm talking about a constant speed prop on a single engine
> aircraft, in this case a Mooney 201. Windmill RPM was about 800, and no
> amount of pulling on the prop control would change that RPM. Obviously, if
> the RPM doesn't change, the prop pitch didn't change, and the glide is not
> affected.
>
> Jim and I have 'round on this one before, but I stand by my observations.

Well, here's another data point on the same make and model, M20J. I don't have
the numbers to go with my observation, but subjectively when I pull the prop
control back at engine idle and ~best-glide, it feels like I just disengaged the
brakes.

On 7/17/2006 11:48 AM, Dave Butler wrote the following:
> Al wrote:
>
>> There is indeed. In my experience, cycling the prop on a windmilling
>> engine has no effect. I'm talking about a constant speed prop on a
>> single engine aircraft, in this case a Mooney 201. Windmill RPM was
>> about 800, and no amount of pulling on the prop control would change
>> that RPM. Obviously, if the RPM doesn't change, the prop pitch didn't
>> change, and the glide is not affected.
>>
>> Jim and I have 'round on this one before, but I stand by my observations.
>
> Well, here's another data point on the same make and model, M20J. I
> don't have the numbers to go with my observation, but subjectively when
> I pull the prop control back at engine idle and ~best-glide, it feels
> like I just disengaged the brakes.

Yes. That's the way it felt in the 182. I don't have any numbers but
the effect was not subtle. Hence my initial post.

Al wrote:

> There is indeed. In my experience, cycling the prop on a windmilling engine
> has no effect. I'm talking about a constant speed prop on a single engine
> aircraft, in this case a Mooney 201. Windmill RPM was about 800, and no
> amount of pulling on the prop control would change that RPM. Obviously, if
> the RPM doesn't change, the prop pitch didn't change, and the glide is not
> affected.

Certainly seems to make a difference on an idling engine. I expect
that my engine at idle is not developing much thrust (for she'll die
when it's hot once I roll out unless I give her a little gas).

If your engine won't reliably idle, there is something
wrong. The idle is set too low or the idle mixture circuit
is plugged. If it is an injected engine the fuel pump may
have low pressure.


--
James H. Macklin
ATP,CFI,A&P

"Ron Natalie" > wrote in message
...
| Al wrote:
|
| > There is indeed. In my experience, cycling the prop on a
windmilling engine
| > has no effect. I'm talking about a constant speed prop
on a single engine
| > aircraft, in this case a Mooney 201. Windmill RPM was
about 800, and no
| > amount of pulling on the prop control would change that
RPM. Obviously, if
| > the RPM doesn't change, the prop pitch didn't change,
and the glide is not
| > affected.
|
| Certainly seems to make a difference on an idling engine.
I expect
| that my engine at idle is not developing much thrust (for
she'll die
| when it's hot once I roll out unless I give her a little
gas).

In article >,
Ron Natalie > wrote:

> Al wrote:
>
> > There is indeed. In my experience, cycling the prop on a windmilling engine
> > has no effect. I'm talking about a constant speed prop on a single engine
> > aircraft, in this case a Mooney 201. Windmill RPM was about 800, and no
> > amount of pulling on the prop control would change that RPM. Obviously, if
> > the RPM doesn't change, the prop pitch didn't change, and the glide is not
> > affected.
>
> Certainly seems to make a difference on an idling engine. I expect
> that my engine at idle is not developing much thrust (for she'll die
> when it's hot once I roll out unless I give her a little gas).

Ron, is your engine injected?
If it is, you need to adjust the idle mixture to prevent the starvation.

john smith wrote:
> In article >,
> Ron Natalie > wrote:
>
>> Al wrote:
>>
>>> There is indeed. In my experience, cycling the prop on a windmilling engine
>>> has no effect. I'm talking about a constant speed prop on a single engine
>>> aircraft, in this case a Mooney 201. Windmill RPM was about 800, and no
>>> amount of pulling on the prop control would change that RPM. Obviously, if
>>> the RPM doesn't change, the prop pitch didn't change, and the glide is not
>>> affected.
>> Certainly seems to make a difference on an idling engine. I expect
>> that my engine at idle is not developing much thrust (for she'll die
>> when it's hot once I roll out unless I give her a little gas).
>
> Ron, is your engine injected?
> If it is, you need to adjust the idle mixture to prevent the starvation.

Yes, it is actually probably too rich at idle. It's on my list, it
only happens on excessively hot days.