Leaning for taxi

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)

I have always started up my 182C 0-470 about 1" from full rich.
Then, always lean to taxi.
And, I lean at full power during run up. None of this girly man 1700
rpm stuff.

Alan Bloom
Dogs can fly.
http://www.flyingmutts.com




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

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.

I lean for taxi, but I did learn one lesson. On one occasion soon after I
started the practice, the engine quit when I applied power to get the wheels
rolling. The passenger wasn't impressed. Now I lean a little less.

-- David Brooks

I lean for taxi, but I did learn one lesson. On one occasion soon after I
started the practice, the engine quit when I applied power to get the wheels
rolling. The passenger wasn't impressed. Now I lean a little less.

-- David Brooks

Despite your passenger's opinion, this is actually best practice since
it prevents you from taking off if you forget to enrich for the
takeoff. I know, I know, that's what checklists are for, but who
among us has never skipped an item on a checklist?

Hi,

I have learned from my intructor to lean for taxi, and I regularly do so. I
do so while waiting for take-off as well. One trick that I use (also learned
from my instructor) while waiting, is to place my checklist between throttle
and mixture, that way I don't forget to enrich. And also use my hand to push
everything forward at the same time (throttle, mixture, and with little
finger carb heat).
Usually fly Piper Cherokee 140MOD with 160HP Lycoming engine.

Regards,
Shkumbin, EFHF
PPL(A)-SEP,
Delete DELTA from email to reply.

P.S. Regarding skipping items from checklist: I have done it so in several
occasions, but once I got a bit scared during take-off roll. I skipped the
TRIM to Neutral item, and while on a take-off roll I got some "strange"
behaviour...the nose trim was at quite heavy Nose Up position. It took me
few seconds to realize that. For the moment I thought that the elevator got
somehow jammed. Since than I check the Trim three times at least...and never
skip an item from checklist. But I am still a novice, barely 100hours, so my
discipline will fade with time I guess...

"PaulH" wrote in message
om...

I lean for taxi, but I did learn one lesson. On one occasion soon after
I
started the practice, the engine quit when I applied power to get the
wheels
rolling. The passenger wasn't impressed. Now I lean a little less.

-- David Brooks

Despite your passenger's opinion, this is actually best practice since
it prevents you from taking off if you forget to enrich for the
takeoff. I know, I know, that's what checklists are for, but who
among us has never skipped an item on a checklist?

"PaulH" wrote in message
om...

I lean for taxi, but I did learn one lesson. On one occasion soon after
I
started the practice, the engine quit when I applied power to get the
wheels
rolling. The passenger wasn't impressed. Now I lean a little less.

-- David Brooks

Despite your passenger's opinion, this is actually best practice since
it prevents you from taking off if you forget to enrich for the
takeoff. I know, I know, that's what checklists are for, but who
among us has never skipped an item on a checklist?

Well, sure, it prevents you from taking off because you can only taxi 2 or 3
feet from the parking space, and never get to runup. You then have the wear
on the battery and started all over again.

But I take your point.

-- David Brooks

David,

Well, sure, it prevents you from taking off because you can only taxi 2 or 3
feet from the parking space, and never get to runup.


How? it's real easy to lean to a point where you can taxi without problems but
not advance power to full. if you need full power for taxi, you have a
different set of problems...

--
Thomas Borchert (EDDH)

"Thomas Borchert" wrote in message
...
David,

Well, sure, it prevents you from taking off because you can only taxi 2
or 3
feet from the parking space, and never get to runup.


How? it's real easy to lean to a point where you can taxi without problems
but
not advance power to full. if you need full power for taxi, you have a
different set of problems...

Yes, but my point was it's also real easy to lean to past that point. That
was the scenario - I had leaned too well after startup and the engine
stopped after we had moved a few feet. Of course I can lean enough to allow
taxi, but I don't know of a way of getting the right setting for taxi while
I'm standing still. You have to use the TLAR (That Looks About Right)
method, which takes experience.

-- David Brooks

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


We're running an O-360 with an Ellison throttle-body injector... after start
we just pull the mixture nearly all the way out and taxi around like that
(the engine really doesn't like full rich on the ground). It stays there
till runup, and then after landing I usually lean out even before I clear
the runway. The RPM gain is significant when I do this; a full-rich idle
will sit somewhere between 500 and 600, and after leaning it will go to
around 900. With the mixture full out, you can get up to about 1300 RPM
before it starts to sag--this is good for clearing the plugs at the end of a
flight just before shutdown.