Leaning for taxi

Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q

Hi Jim,

I'm at 2V2 as well. I lean for taxi in my TR-182, (IO-540) although not as
aggressively as you seem to. Full rich for takeoff, because of the turbo.

By the way, I'm always looking for a safety pilot if you want to trade some
time...

Michael


"Jim Rosinski" wrote in message
om...
Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q

"Jim Rosinski" wrote in message
om...
Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q

A buddy at work and I are both pilots, and we rent two different Skyhawks.
He told be about a similar experience.
His instructor (and owner) told him that a plug in one cylinder kept
fouling, and at runup, put it up to 2500 for 20 seconds to clear it out.
I don't know if this is at all similar, but just rang a bell for some
reason...

Adam

"Full rich for taxi" is an anachronism. Always lean for taxi.

Bob Gardner

"Jim Rosinski" wrote in message
om...
Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q

In article ,
Jim Rosinski wrote:
I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,

I started doing this when I bought my plane. Eventually I quit pushing
the mixture to full rich at start. I only push it in about an inch now
when it first catches, and I don't advance it until I do the runup.

--
Ben Jackson

http://www.ben.com/

"Jim Rosinski" wrote in message
om...
Earlier this summer I had a problem with a 400 rpm or so mag drop
during runup. Leaning aggressively at 2100 rpm solved the problem, but
it recurred on numerous occasions. I tried leaning aggressively during
all taxi operations, to the point that the engine would barely run,
and that seems to have solved the problem. No unacceptable mag drop
now for the past month. And a lower throttle setting can be used to
achieve the same taxi rpm as in the past, where the leaning procedure
was "pull the mixture out an inch or so from full rich" (my home base,
2V2, is just over 5000 feet elevation). But I still use the same "lean
to peak rpm then enrichen slightly" pre-takeoff procedure as I always
have at this altitude.

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Summertime density altitude at KEDW is almost always over 5Kft.
We pull the mixture out before we leave the chocks.

On 5 Sep 2004 16:46:24 -0700, (Jim Rosinski) wrote:

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Jim Rosinski
N3825Q

Here are COS (elv 6100), we don't even start the engine at full rich.
We keep it about an inch out when we crank up on the 172's. Then I
even lean it a little more for the taxi. then I perform the run up and
lean as recommended. I have yet seen a fouled plug on run up doing
this in over 2 years.

Scott D,

You may have an ignition problem occurring that is being masked by
running the engine for a while, so that it appears that running lean
for a while clears it up. You may want to have your plugs tested at
your next oil change (or sooner).

Jim,

What do folks think of this procedure? Can it harm the engine?


Good procedure. You cannot harm an engine by leaning it during taxi.

You might want your mechanic to adjust idle mixture. If, at idle, you
pull out the mixture slowly, you should see a 25 to 50 rpm rise in RPM
just before the engine quits - that's the correct setting. OTOH, if you
adjust it for your field altitude, you might have problems at lower
altitude fields.

--
Thomas Borchert (EDDH)

What do folks think of this procedure? Can it harm the engine? It's a
Lycoming O320-D2G in a Skyhawk. Thanks in advance.

Can you get the autogas STC for that engine?

We had the O320 in our Warrior, and unleaded autogas completely eliminated
failed mag checks, and the need to lean over-aggressively.

And, of course, it saves you ten bucks an hour.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"