Emergency Procedures

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?

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?

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

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.

"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.

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).

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

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?