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?

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
news | 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.