Leaning / step climbing?

Hi all:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. When I am entirely free of the Class
B, I pick a VFR cruising altitude that is appropriate, and at that
point I lean the engine out on the 172. My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

aw

For the SR22, there's a specific fuel flow setting (mix adjustment) for
every 4000' to generate max power. So, leaning at various altitudes.

I used a similar though not nearly so precise approach to climb settings in
my Grumman Tiger. Just mind the EGT/CHTs.

--
Patrick Flynn
Sammamish, WA
Cirrus SR22 N6099Z KRNT

"aaronw" wrote in message
...
Hi all:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. When I am entirely free of the Class
B, I pick a VFR cruising altitude that is appropriate, and at that
point I lean the engine out on the 172. My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

aw

My engine is notorious for spark plug fouling (200hp Lycoming IO-360), so
I lean whenever I (1) level off or (2) exceed 5000' MSL in climb. This is
as per Lycoming's recommednations. If I level off and lean below 5000' and
then climb again, I go full rich until I level off again or climb above
5000'. This procedure can be a pain, but it keeps things running smooth
and keeps the plugs clean.

Best regards,

Steve Robertson
N4732J 1967 Beechcraft Musketeer Super III

aaronw wrote:

Hi all:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. When I am entirely free of the Class
B, I pick a VFR cruising altitude that is appropriate, and at that
point I lean the engine out on the 172. My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

aw

Aaronw,

You might take note of the EGT indication during your initial climb.
Then, when you climb further and leave the power setting as it is, the
EGT will drop. It would be safe to lean so much that the EGT setting
will climb back to the take-off value. Howeever, you should probably
select a climb speed higher than Vy in order to cool the engine better.

--
Thomas Borchert (EDDH)

aaronw wrote in
:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. ... should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

Most Class-B's have that little trick. They never "quite" let you in...
just step you up right below the floor.

The answer to your question in part depends upon how long you are going
to be in cruise at each altitude, and how big the step climb is. If the
steps are small, and far apart, then you can lean some and probably
still climb without going back to a richer setting. [Remember, it will
be getting richer automatically as you climb.] With something like a
1000 foot climb, if I am at reduced RPM, I will probably just leave it
there for the climb - whereas if I am climbing 10K feet I will certainly
want to go back to max RPM.

Another suggestion - consider climbing at a cruise-climb rate. You will
get out from under the shelf faster and keep the engine cooler. Ideally
you will just sort of "continue" your climb from sector to sector.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

Aaron,

The more reasonable question is "why not lean"? Leaning the mixture
in most airplanes to at least a ballpark location doesn't take long at
all and should be a part of setting the power every time one flies
level. Yes, when departing under circumstances where you have a
number of level flight periods and then short climbs, you are messing
with the power frequently. But, leaning produces good things, such as
avoiding fouled plugs and extending your range and endurance,
something you may be profoundly grateful for someday. If you are
running at 65% power or less, you absolutely cannot hurt the engine by
leaning it wrong, it will quit before it detonates. At 75% power
simply shoot for about 100 degrees rich of peak and you will get best
power while not getting the high temps and pressures you get at 50
degrees rich of peak. For most 172s you probably aren't going to
operate lean of peak as the engine usually runs roughly and is
uncomfortable. So, for each place where you level off, go ahead and
lean. Enrichen appropriately for the next climb. At cruise set the
mixture where you want it for the power setting you are using.
What's nice is that you can usually just leave the mixture knob in
that position for the rest of the flight, until you are on short final
at which time you may want to enrichen it in the event you make a go
around.

Go ahead and lean the mixture, why waste fuel?

All the best,
Rick

aaronw wrote in message . ..
Hi all:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. When I am entirely free of the Class
B, I pick a VFR cruising altitude that is appropriate, and at that
point I lean the engine out on the 172. My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

aw

aaronw wrote:

My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

I have a Maule with a Lycoming O-320. I lean whenever I can and enrichen the
mixture for climb. If I know that I'll be climbing again in a few minutes, I
don't go through the entire procedure of leaning until it stumbles and then
enrichening until it's smooth, however. I just pull the red knob back using
the TLAR ("that looks about right") method.

George Patterson
If you're not part of the solution, you can make a lot of money prolonging
the problem.

always lean... during climbs..

we use a Pawnee with 235HP fixed pitch prop for towing gliders, we start at
2800MSL, and it is noticeable to lean above 4000MSL, (1200AGL), during the
climb I watch the RPM and lean for peak rpm in the full throttle climb and
then "bump" it rich, as we are always climbing.

Some will argue it is not needed to lean below 3000MSL.. for your area.. but
lean to peak RPM if the temp gauge is out.

BT
"aaronw" wrote in message
...
Hi all:

I fly underneath a Class B airspace (Washington). My question is that
while I am leaving the area on a flight, I will often end up climbing
up higher as I get further from my departure airport as I get under
the shelves that are higher up. When I am entirely free of the Class
B, I pick a VFR cruising altitude that is appropriate, and at that
point I lean the engine out on the 172. My question is, knowing that
I will have frequent full power applications to climb out to higher
altitudes, 1000 - 2000 - 2500 - 3000, etc., should I lean at each
altitude, or is it better to just let it go until I have stabilized at
my cruising altitude and then lean accordingly?

aw

Btiz,

Some will argue it is not needed to lean below 3000MSL..


Uh, only those clinging to one of the more stupid OWTs (Old Wive's
Tale).

--
Thomas Borchert (EDDH)

Some will argue it is not needed to lean below 3000MSL..

Fuel calculations are based on a properly leaned engine. You may come up short
if you don't lean.

Jose

--
(for Email, make the obvious changes in my address)