"Guillermo" > wrote:
>> Perhaps... but what if you're in IMC and partial panel?

My initial thought was "one emergency at a time, please". If you're
partial panel in IMC and you then lose the engine, you're goose is probably
cooked anyway.

But, then I realized that any engine failure (in a typical 6-pack equipped
piston single) is going to involve loss of vacuum, so you're going to be
partial panel anyway.

It's a worthwhile exercise to practice an engine-out instrument approach.
I haven't practiced one in quite a while myself, so I should put that on my
list for my next practice flight. Basicly, set up for best glide, go GPS
direct to the nearest airport, and hope luck is on your side.

Roy Smith wrote:
> "Guillermo" > wrote:
>
>>>Perhaps... but what if you're in IMC and partial panel?
>
>
> My initial thought was "one emergency at a time, please". If you're
> partial panel in IMC and you then lose the engine, you're goose is probably
> cooked anyway.
>
> But, then I realized that any engine failure (in a typical 6-pack equipped
> piston single) is going to involve loss of vacuum, so you're going to be
> partial panel anyway.

Why? I believe most vacuum pumps are mechanically driven from the
engine so as long as the engine is turning, there should be vacuum. If
the failure is due to fuel or spark, then I don't see a vacuum loss.
Likewise, a "light" mechanical failure (valve, rocker arm, etc.), that
doesn't impede crank rotation also shouldn't cause vacuum loss. Now, if
you break the crank, throw a rod, or lose oil, then I can see the
likelihood, or even certainty, of the engine rotation ceasing and the
vacuum pump ceasing with it.

I'mnot suggesting that you shouldn't practice power off instrument
approaches though!

Matt

So what you are saying is that a windmilling engine is going to produce
enough vacuum to run the gyros? I think not...

Jon Kraus
'79 Money 201
4443H @ TYQ


Matt Whiting wrote:
> Roy Smith wrote:
>
>> "Guillermo" > wrote:
>>
>>>> Perhaps... but what if you're in IMC and partial panel?
>>
>>
>>
>> My initial thought was "one emergency at a time, please". If you're
>> partial panel in IMC and you then lose the engine, you're goose is
>> probably cooked anyway.
>>
>> But, then I realized that any engine failure (in a typical 6-pack
>> equipped piston single) is going to involve loss of vacuum, so you're
>> going to be partial panel anyway.
>
>
> Why? I believe most vacuum pumps are mechanically driven from the
> engine so as long as the engine is turning, there should be vacuum. If
> the failure is due to fuel or spark, then I don't see a vacuum loss.
> Likewise, a "light" mechanical failure (valve, rocker arm, etc.), that
> doesn't impede crank rotation also shouldn't cause vacuum loss. Now, if
> you break the crank, throw a rod, or lose oil, then I can see the
> likelihood, or even certainty, of the engine rotation ceasing and the
> vacuum pump ceasing with it.
>
> I'mnot suggesting that you shouldn't practice power off instrument
> approaches though!
>
> Matt

Jon Kraus wrote:

> So what you are saying is that a windmilling engine is going to
> produce enough vacuum to run the gyros? I think not...

Since the vacuum pump on most of our engines (an O-360 in my plane -
something similar in your Mooney) are run by a gear on the engine, as
long as the engine is spinning, the pump will be spinning. When I do my
runup, I get 5" of vacuum at anything over 1500 RPM or so - certainly at
1700 RPM or above.

So, as long as my engine windmills at more than 1500 RPM, I'll have more
than enough vacuum to run my gyros. And it does - I've tried it.

Try it yourself if you think not.....

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2005

On Wed, 26 Oct 2005 03:14:11 GMT, "Marc J. Zeitlin"
> wrote:

>Jon Kraus wrote:
>
>> So what you are saying is that a windmilling engine is going to
>> produce enough vacuum to run the gyros? I think not...
>
>Since the vacuum pump on most of our engines (an O-360 in my plane -
>something similar in your Mooney) are run by a gear on the engine, as
>long as the engine is spinning, the pump will be spinning. When I do my
>runup, I get 5" of vacuum at anything over 1500 RPM or so - certainly at
>1700 RPM or above.
>
>So, as long as my engine windmills at more than 1500 RPM, I'll have more
>than enough vacuum to run my gyros. And it does - I've tried it.
>
>Try it yourself if you think not.....


You think wrong, Jon. Even at idle, most vacuum pumps produce enough
differential to keep rotors spinning satisfactorily.

"Marc J. Zeitlin" > wrote in message
...
> Jon Kraus wrote:
>
> > So what you are saying is that a windmilling engine is going to
> > produce enough vacuum to run the gyros? I think not...
>
> Since the vacuum pump on most of our engines (an O-360 in my plane -
> something similar in your Mooney) are run by a gear on the engine, as
> long as the engine is spinning, the pump will be spinning. When I do my
> runup, I get 5" of vacuum at anything over 1500 RPM or so - certainly at
> 1700 RPM or above.
>
> So, as long as my engine windmills at more than 1500 RPM, I'll have more
> than enough vacuum to run my gyros. And it does - I've tried it.
>
You've tried turning off your engine and have your propeller spinning at
more than 1500 RPM?
That seems unlikely, when you do a simulated engine failure with the engine
idling, you do get more RPM than in the ground, but not even close to 1500
RPM... I can't imagine that the engine will spin more than 1000 RPM (or a
lot less) in a real engine failure

On Mon, 31 Oct 2005 07:17:02 -0500, "Guillermo"
> wrote:

>
>"Marc J. Zeitlin" > wrote in message
...
>> Jon Kraus wrote:
>>
>> > So what you are saying is that a windmilling engine is going to
>> > produce enough vacuum to run the gyros? I think not...
>>
>> Since the vacuum pump on most of our engines (an O-360 in my plane -
>> something similar in your Mooney) are run by a gear on the engine, as
>> long as the engine is spinning, the pump will be spinning. When I do my
>> runup, I get 5" of vacuum at anything over 1500 RPM or so - certainly at
>> 1700 RPM or above.
>>
>> So, as long as my engine windmills at more than 1500 RPM, I'll have more
>> than enough vacuum to run my gyros. And it does - I've tried it.
>>
>You've tried turning off your engine and have your propeller spinning at
>more than 1500 RPM?
>That seems unlikely, when you do a simulated engine failure with the engine
>idling, you do get more RPM than in the ground, but not even close to 1500
>RPM... I can't imagine that the engine will spin more than 1000 RPM (or a
>lot less) in a real engine failure
>
That's one of the reasons I fly approaches faster than VFR patterns.
At idle (with windmilling prop) the vacuum drops below the red line.
Now that doesn't mean I lose instruments immediately, but it'd get
pretty iffy doing a complete ILS at idle. With an engine failure I
wouldn't want to have to let down through a thick layer without a
second vacuum pump or backup electrical AI.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

You think wrong Bill. At least on my Mooney at idle doesn't come close
to the vacuum gauge reading in the green. This is with a new dry pump
too. I still doubt that a windmilling engine will keep the gyros spooled
up enough to run the AI and DG. Just my .02. YMMV

Jon Kraus
'79 Mooney 201
4443H @ TYQ

Bill Zaleski wrote:

>
> You think wrong, Jon. Even at idle, most vacuum pumps produce enough
> differential to keep rotors spinning satisfactorily.

Marc J. Zeitlin wrote:
> Jon Kraus wrote:
>
>
>>So what you are saying is that a windmilling engine is going to
>>produce enough vacuum to run the gyros? I think not...
>
>
> Since the vacuum pump on most of our engines (an O-360 in my plane -
> something similar in your Mooney) are run by a gear on the engine, as
> long as the engine is spinning, the pump will be spinning. When I do my
> runup, I get 5" of vacuum at anything over 1500 RPM or so - certainly at
> 1700 RPM or above.
>
> So, as long as my engine windmills at more than 1500 RPM, I'll have more
> than enough vacuum to run my gyros. And it does - I've tried it.
>
> Try it yourself if you think not.....
>

You are not even going to get close to 1500 RPM by windmilling. Not
without diving at the ground and being well above Vg. At least I
wouldn't in the 152.

-Brooks

Jon Kraus wrote:

> You think wrong Bill. At least on my Mooney at idle doesn't come close
> to the vacuum gauge reading in the green. This is with a new dry pump
> too. I still doubt that a windmilling engine will keep the gyros spooled
> up enough to run the AI and DG. Just my .02. YMMV
>
> Jon Kraus
> '79 Mooney 201
> 4443H @ TYQ
>
> Bill Zaleski wrote:
>
>>
>> You think wrong, Jon. Even at idle, most vacuum pumps produce enough
>> differential to keep rotors spinning satisfactorily.
>
>

Same with the club Arrow I fly. It takes 1200 or so to get the vacuum
into the green.

Matt

I never said that you will get "green line "vacuum. I did say that
the gyro's will continue to work with the vacuum that you will have
with a windmilling engine. Go to 10K, windmill, and see that you still
have useable gyro's. Been there, done that, they still work.


On Tue, 01 Nov 2005 11:48:38 GMT, Jon Kraus >
wrote:

>You think wrong Bill. At least on my Mooney at idle doesn't come close
>to the vacuum gauge reading in the green. This is with a new dry pump
>too. I still doubt that a windmilling engine will keep the gyros spooled
>up enough to run the AI and DG. Just my .02. YMMV
>
>Jon Kraus
>'79 Mooney 201
>4443H @ TYQ
>
>Bill Zaleski wrote:
>
>>
>> You think wrong, Jon. Even at idle, most vacuum pumps produce enough
>> differential to keep rotors spinning satisfactorily.

On 11/1/2005 17:43, Bill Zaleski wrote:

> I never said that you will get "green line "vacuum. I did say that
> the gyro's will continue to work with the vacuum that you will have
> with a windmilling engine. Go to 10K, windmill, and see that you still
> have useable gyro's. Been there, done that, they still work.

How long did you windmill? After all, the gyros are going to
continue to spin for some time with no vacuum. The slower they go,
the more difficulty they're going to have.

Did you go for more than 5 or 10 minutes and verify that they were
still working acceptably?


>
>
> On Tue, 01 Nov 2005 11:48:38 GMT, Jon Kraus >
> wrote:
>
>>You think wrong Bill. At least on my Mooney at idle doesn't come close
>>to the vacuum gauge reading in the green. This is with a new dry pump
>>too. I still doubt that a windmilling engine will keep the gyros spooled
>>up enough to run the AI and DG. Just my .02. YMMV
>>
>>Jon Kraus
>>'79 Mooney 201
>>4443H @ TYQ
>>
>>Bill Zaleski wrote:
>>
>>>
>>> You think wrong, Jon. Even at idle, most vacuum pumps produce enough
>>> differential to keep rotors spinning satisfactorily.
>


--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

Yup. Right to the ground from 10K' bout 800FPM

Bill Z. A&P I.A.

On Wed, 02 Nov 2005 07:46:24 -0800, Mark Hansen
> wrote:

>On 11/1/2005 17:43, Bill Zaleski wrote:
>
>> I never said that you will get "green line "vacuum. I did say that
>> the gyro's will continue to work with the vacuum that you will have
>> with a windmilling engine. Go to 10K, windmill, and see that you still
>> have useable gyro's. Been there, done that, they still work.
>
>How long did you windmill? After all, the gyros are going to
>continue to spin for some time with no vacuum. The slower they go,
>the more difficulty they're going to have.
>
>Did you go for more than 5 or 10 minutes and verify that they were
>still working acceptably?
>
>
>>
>>
>> On Tue, 01 Nov 2005 11:48:38 GMT, Jon Kraus >
>> wrote:
>>
>>>You think wrong Bill. At least on my Mooney at idle doesn't come close
>>>to the vacuum gauge reading in the green. This is with a new dry pump
>>>too. I still doubt that a windmilling engine will keep the gyros spooled
>>>up enough to run the AI and DG. Just my .02. YMMV
>>>
>>>Jon Kraus
>>>'79 Mooney 201
>>>4443H @ TYQ
>>>
>>>Bill Zaleski wrote:
>>>
>>>>
>>>> You think wrong, Jon. Even at idle, most vacuum pumps produce enough
>>>> differential to keep rotors spinning satisfactorily.
>>

"Mark Hansen" > wrote in message ...
> On 11/1/2005 17:43, Bill Zaleski wrote:
>
>> I never said that you will get "green line "vacuum. I did say that
>> the gyro's will continue to work with the vacuum that you will have
>> with a windmilling engine. Go to 10K, windmill, and see that you still
>> have useable gyro's. Been there, done that, they still work.
>
> How long did you windmill? After all, the gyros are going to
> continue to spin for some time with no vacuum. The slower they go,
> the more difficulty they're going to have.
>
> Did you go for more than 5 or 10 minutes and verify that they were
> still working acceptably?
>

My gyros spin up from stopped to a usable state while my engines idle after startup.
Don't yours?

On 11/2/2005 08:33, John R. Copeland wrote:

> "Mark Hansen" > wrote in message ...
>> On 11/1/2005 17:43, Bill Zaleski wrote:
>>
>>> I never said that you will get "green line "vacuum. I did say that
>>> the gyro's will continue to work with the vacuum that you will have
>>> with a windmilling engine. Go to 10K, windmill, and see that you still
>>> have useable gyro's. Been there, done that, they still work.
>>
>> How long did you windmill? After all, the gyros are going to
>> continue to spin for some time with no vacuum. The slower they go,
>> the more difficulty they're going to have.
>>
>> Did you go for more than 5 or 10 minutes and verify that they were
>> still working acceptably?
>>
>
> My gyros spin up from stopped to a usable state while my engines idle after startup.
> Don't yours?
>

What is usable? The AI usually doesn't straighten-up 100% until after
I do my static run-up.

However, the real sign is the vacuum gage. It reads below the green while
idling. Now, the gyros are still spinning even while the vacuum is not
in the green - but I wouldn't want to bet my life on them while in IMC
conditions ... I may have to, but I wouldn't assume they are working 100%
while the vacuum is below the green.


--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

"Mark Hansen" > wrote in message ...
> On 11/2/2005 08:33, John R. Copeland wrote:
>
>> "Mark Hansen" > wrote in message ...
>>> On 11/1/2005 17:43, Bill Zaleski wrote:
>>>
>>>> I never said that you will get "green line "vacuum. I did say that
>>>> the gyro's will continue to work with the vacuum that you will have
>>>> with a windmilling engine. Go to 10K, windmill, and see that you still
>>>> have useable gyro's. Been there, done that, they still work.
>>>
>>> How long did you windmill? After all, the gyros are going to
>>> continue to spin for some time with no vacuum. The slower they go,
>>> the more difficulty they're going to have.
>>>
>>> Did you go for more than 5 or 10 minutes and verify that they were
>>> still working acceptably?
>>>
>>
>> My gyros spin up from stopped to a usable state while my engines idle after startup.
>> Don't yours?
>>
>
> What is usable? The AI usually doesn't straighten-up 100% until after
> I do my static run-up.
>
> However, the real sign is the vacuum gage. It reads below the green while
> idling. Now, the gyros are still spinning even while the vacuum is not
> in the green - but I wouldn't want to bet my life on them while in IMC
> conditions ... I may have to, but I wouldn't assume they are working 100%
> while the vacuum is below the green.
>

Roger that.
Do you have any possibility of changing to a higher-capacity vacuum pump?
(I assume your instrument filters aren't clogged, of course.)
I show 5 inches Hg of vacuum at engine idle in my airplane.

On 11/2/2005 09:02, John R. Copeland wrote:

> "Mark Hansen" > wrote in message ...
>> On 11/2/2005 08:33, John R. Copeland wrote:
>>
>>> "Mark Hansen" > wrote in message ...
>>>> On 11/1/2005 17:43, Bill Zaleski wrote:
>>>>
>>>>> I never said that you will get "green line "vacuum. I did say that
>>>>> the gyro's will continue to work with the vacuum that you will have
>>>>> with a windmilling engine. Go to 10K, windmill, and see that you still
>>>>> have useable gyro's. Been there, done that, they still work.
>>>>
>>>> How long did you windmill? After all, the gyros are going to
>>>> continue to spin for some time with no vacuum. The slower they go,
>>>> the more difficulty they're going to have.
>>>>
>>>> Did you go for more than 5 or 10 minutes and verify that they were
>>>> still working acceptably?
>>>>
>>>
>>> My gyros spin up from stopped to a usable state while my engines idle after startup.
>>> Don't yours?
>>>
>>
>> What is usable? The AI usually doesn't straighten-up 100% until after
>> I do my static run-up.
>>
>> However, the real sign is the vacuum gage. It reads below the green while
>> idling. Now, the gyros are still spinning even while the vacuum is not
>> in the green - but I wouldn't want to bet my life on them while in IMC
>> conditions ... I may have to, but I wouldn't assume they are working 100%
>> while the vacuum is below the green.
>>
>
> Roger that.
> Do you have any possibility of changing to a higher-capacity vacuum pump?
> (I assume your instrument filters aren't clogged, of course.)
> I show 5 inches Hg of vacuum at engine idle in my airplane.
>

Naw, Rental. C-172M

--
Mark Hansen, PP-ASEL, Instrument Airplane
Sacramento, CA

John R. Copeland wrote:

> My gyros spin up from stopped to a usable state while my engines idle after startup.
> Don't yours?
>
You would hope so, because otherwise you're going to be in deep doodoo
climbing up into the soup shortly after takeoff.

Mark Hansen wrote:

>
> What is usable? The AI usually doesn't straighten-up 100% until after
> I do my static run-up.

Probably not the run-up but the elapsed time. It takes on the order of
ten minutes for the gyros to stableize.

>
> However, the real sign is the vacuum gage. It reads below the green while
> idling.

Fix your pump.

Mark Hansen wrote:

>
> What is usable? The AI usually doesn't straighten-up 100% until after
> I do my static run-up.

Then you got a bad gyro. My AI shakes like a son of a bitch for about
10 seconds and then settles down in the upright position. Idles speed
about 900. Vacuum gauge will be bottom of the green at 1000 rpm.