Nasa Icing courses

Argh. Wouldn't you think there would be SOME science to this?

If there is, it's available from Lycoming or Continental for your engine.
Not from "my A&P says...."

Well, I am blessed to have an A&P who:

1. Doesn't work on little planes cuz he needs the money.
2. Is an award-winning home builder
3. Has 40 years in the business
4. Is an accomplished pilot
5. Has rebuilt over 100 O-540s, including mine.

What he says about engines is, in my world, gospel.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Stan Prevost wrote:
"Jim Macklin" wrote in message
news:Wgcwf.40975$QW2.5751@dukeread08...

point and then pull the mixture to shut it down. That
should show a slight 25-50 rpm increase just as it shuts
down since idle should be a little rich.

For my TIO540-S1AD, Lycoming says five rpm, not more than ten.

The mixture on injected engines typically is not as rich at idle as carburetted
engines, so the rpm increase should not be as great.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

"Jay Honeck" wrote in message
news:Hxkwf.474673$084.253721@attbi_s22...

Isn't that a stitch? Your A&P says 1000 RPM is too *slow* for proper
lubrication. Jim Macklin (and many others) says it may be too *fast* to
run your engine before proper lubrication has occurred. Who is right?


Your O-540 is probably better at oil distribution than my O-235. Your
engine is substantially larger and more expensive. They can afford to give
it a better oiling system than exists in a smaller, cheaper engine.

As for trusting Lycoming to tell us: I believe they have a commitment to
safety, but they also make money from parts, like cam shafts. Adding to
that, summer is much different than winter oil at startup, not to mention
cylinder clearances. On startup, do you want the cylinders to wear out
faster, or would you rather protect your cam? You may not be able to have
both in an optimum fashion on some engines. Less RPM may help the
cylinders, but leave the cam with less lubrication. It makes me wish that
all cams had a direct spray oil system, and that there was an electric oil
pump that could be used to lubricate the engine prior to startup.

Paul Missman

With the low rpm, air flow in the manifold is not smooth or
steady. A carb meters fuel based on volume and the engine
burns fuel by mass. Getting balanced and safe fuel mixture
in each cylinder with a carb is not easy, they tend to meter
a little extra at all power settings. Aircraft injection is
usually constant flow port injection, but it is more precise
and the fuel is dumped into the intake manifold just at the
intake valve. The automotive and newer aircraft systems
have controlled injectors which only squirt fuel as needed,
making even more accurate distribution.
Diesel and the big radial engines late in WWII/until the
1950's had direct injection into the combustion chamber.
[Most radials used a pressure carb [fuel injection with the
nozzle in the throttle body] or port injection.]


--
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.




"George Patterson" wrote in message
news:Volwf.18567$em5.10846@trnddc05...
| Stan Prevost wrote:
| "Jim Macklin"
wrote in message
| news:Wgcwf.40975$QW2.5751@dukeread08...
|
| point and then pull the mixture to shut it down. That
| should show a slight 25-50 rpm increase just as it shuts
| down since idle should be a little rich.
|
| For my TIO540-S1AD, Lycoming says five rpm, not more
than ten.
|
| The mixture on injected engines typically is not as rich
at idle as carburetted
| engines, so the rpm increase should not be as great.
|
| George Patterson
| Coffee is only a way of stealing time that should by
rights belong to
| your slightly older self.

It makes me wish that
all cams had a direct spray oil system, and that there was an electric oil pump that could be used to lubricate the
engine prior to startup.

Paul Missman

You can add a pre-oiler, (at least to some aircraft).

http://www.aircraftspruce.com/catalo...s/proluber.php

I've read of engine modifications for spray nozzles as well but don't have time to find a link right now.




----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

In article .com,
"Jay Honeck" wrote:

I was told ground runs is one of the worst things you can do to an airplane
engine, as it was designed for sustained high RPM operations, not ground
run RPMS.

You know, I've heard that since Day One of ownership, too, but ya just
gotta wonder if it's not yet another "old wive's tale", like so many of
these "tried and true" things. How does the engine know the
difference between ground runs at, say 2000 RPM (run-up speed on our
plane) and an extended descent? Is *that* "bad" for the engine, too?

consider the difference in cooling air.

--
Bob Noel
New NHL? what a joke

Ground running does not scavenge the vapors since the vent
system depends on airspeed.



--
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.


"Jay Honeck" wrote in message
oups.com...
| I was told ground runs is one of the worst things you can
do to an airplane
| engine, as it was designed for sustained high RPM
operations, not ground
| run RPMS.
|
| You know, I've heard that since Day One of ownership, too,
but ya just
| gotta wonder if it's not yet another "old wive's tale",
like so many of
| these "tried and true" things. How does the engine know
the
| difference between ground runs at, say 2000 RPM (run-up
speed on our
| plane) and an extended descent? Is *that* "bad" for the
engine, too?
|
| Doesn't running it for 30 minutes on the ground circulate
the oil, and
| prevent corrosion? Can't you get oil temps up to 150 or
better (I
| know, 180 is optimal, but...) with a ground run? Isn't
that better
| than letting it sit and rot till spring?
|
| I fly too often for this to really matter, but I always
wonder if it's
| a real issue or not? Kinda like "shock cooling" and
"pulling the prop
| through" before starting on a cold day... And Marvel
Mystery oil,
| while we're at it...
|
| :-)
| --
| Jay Honeck
| Iowa City, IA
| Pathfinder N56993
| www.AlexisParkInn.com
| "Your Aviation Destination"
|

: Your bad lobe is one of the cam lobes that operates two lifters, so it,
: or its companion will be the first to go in a marginal lubrication
: situation. The lobes depend on oil thrown from the crankshaft cheeks -
: some thing that I don't think happens for a couple of minutes after a
: cool start - especially with a cold engine.

: It isn't a question of how quickly does the oil pump get oil get to the
: cam bearings as journal bearings will retain enough oil to allow them
: to be starved for a minute or two and oil gets there in a few seconds
: anyway.

It's quite unfortunate that the regulations make adding an oil
accumulator/pre-oiler cost-prohibitive for most. Pushing 60-80psi oil from the last
run into the system 30-60 seconds before hitting the starer would help a lot of this.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Jay Honeck wrote:
Running the engine too slow at startup. Apparently, the cams in some
engines get lubrication mainly from the oil splashing around inside the
case. In some engines, 1000 RPM may not be sufficient for full
lubrication after startup. My A&P suggested 1100 - 1200 RPM.


Isn't that a stitch? Your A&P says 1000 RPM is too *slow* for proper
lubrication. Jim Macklin (and many others) says it may be too *fast* to
run your engine before proper lubrication has occurred. Who is right?

And my A&P says 1000 RPM or slower, primarily to save your prop on loose
rocks but also to ensure long engine life.

Argh. Wouldn't you think there would be SOME science to this?

You'd think so, and maybe there is, but if so it hasn't penetrated the pilot
community. Most of what you read is superstition, collective wisdom, common
sense, anecdotal reports, opinion, experiments run with small sample sizes.
Seems the best you can do is to read all the recommendations and try to do the
things that make sense to you. It's frustrating.

Dave

Jay Honeck wrote:

You know, I've heard that since Day One of ownership, too, but ya just
gotta wonder if it's not yet another "old wive's tale", like so many of
these "tried and true" things. How does the engine know the
difference between ground runs at, say 2000 RPM (run-up speed on our
plane) and an extended descent? Is *that* "bad" for the engine, too?

I've wondered that myself. The only big difference that I can think of is that
the circulation of cooling air will be different. As far as long descents is
concerned, I've seen statements that this is harmful due to excessive cooling
and possible plug fouling. Never seen a claim that oil circulation suffers, though.

Doesn't running it for 30 minutes on the ground circulate the oil, and
prevent corrosion? Can't you get oil temps up to 150 or better (I
know, 180 is optimal, but...) with a ground run? Isn't that better
than letting it sit and rot till spring?

As several others have pointed out, circulation of the oil isn't the problem
with the cam lobes. Those are lubricated by splash from the crank. I've never
seen any claims that this differs much from splash while in flight, though.

What I've read is that you really can't get the oil temperature high enough by
running it on the ground. The claim is that ground running adds water and acids
to the oil (flying also does this) and never gets the oil hot enough to vaporize
these. Crankcase ventilation through the breather is also very poor on the
ground; as a result, vapors that do form never leave the crankcase. As another
poster suggested, some form of positive crankcase ventilation would probably
help that.

If the only real issue proves to be the buildup of pollutants in the oil from
ground running, then changing the oil after every other run would take care of
the problem; however, given a choice between this and simply flying the plane
for a few hours, I'd be in the air.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.