Turbo 182: correct mixture for final approach at high altitude?

Peter Duniho wrote:

You do understand that he's talking about a turbocharged engine, right?
Generally speaking, full rich is the correct mixture setting for a
turbocharged piston engine, for full-power takeoffs regardless of altitude.


'Generally speaking', but not necessarily. Full-rich is the correct takeoff
setting for a FUEL-INJECTED engine regardless of altitude, but *not* for a
CARBURETED engine.

Most turbocharged engines are injected, but not all. In fact, the Turbo 182 has
one that isn't: a (carbureted) Lyc 0-540.

Really - my carbureted 182 calls for full rich on takeoff

"Mark Mallory" wrote in message
...


'Generally speaking', but not necessarily. Full-rich is the correct
takeoff
setting for a FUEL-INJECTED engine regardless of altitude, but *not* for a
CARBURETED engine.

Most turbocharged engines are injected, but not all. In fact, the Turbo
182 has
one that isn't: a (carbureted) Lyc 0-540.

Michael 182 wrote:
Really - my carbureted 182 calls for full rich on takeoff

So does mine - at SL on a standard day.

But not on a hot 95 degF afternoon at 5000 MSL.

Peter Duniho wrote:

"john smith" wrote in message
...
[...] Had you need to do a go
around, the cruise mixture would have been sufficient for a full power
go-around.

You do understand that he's talking about a turbocharged engine, right?
Generally speaking, full rich is the correct mixture setting for a
turbocharged piston engine, for full-power takeoffs regardless of altitude.


Yes, I remembered the turbo part this afternoon.
For descent there is no reason to change the mixture unless you are
going to push the throttle back in beyond the cruise power setting.
For takeoff, the turbo should maintain sealevel power up to 12,000 feet
MSL, so full rich or slightly leaned mixture would be used on takeoff. I
think I would still lean for best power prior to releasing brakes for
takeoff.

Michael,

What do you experience that causes you to have to enrichen your
mixture as you descend on your airplane? Are you descending while
carrying a very high power setting? I'm asking because I've flown
T182s and TR182s and have never run into a situation that required
enrichening the mixture during descent unless I leveled off at some
intermediate altitude and went to a relatively high power setting.

Otherwise, the only reason to enrichen the mixture during descent is
if the engine actually begins to run roughly. (See the POH which only
recommends enrichening if you experience engine roughness.) Most
people descend at 65% power or less, which means that it is impossible
to detonate the engine due to lack of heat and pressure, so it's
impossible to run it too lean (it will simply start to run rough and
then quit if you get it too lean, you won't hurt anything). Keeping
it leaned during descent helps avoid overcooling (if you believe in
shock cooling), helps keep the plugs from fouling and doesn't waste
fuel. In general, once you lean the engine for cruise on a T182 you
needn't touch the mixture control until you pull it to idle cutoff
after landing, or to go to full rich on a go around.

All the best,
Rick

"Michael 182" wrote in message news:KXjMb.26563$5V2.40699@attbi_s53...
Are you sure about this? I always have to enrichen the mixture as I decrease
altitude.

Michael


"john smith" wrote in message
...
Barry Klein wrote:

How should we have found the correct mixture setting
for power-off final approach, when the turbo is basically adding no
boost and we are at high density altitude?

Did you enrichen the mixture between cruise and landing?
There should have been no reason to. As you reduce altitude and MP, the
mixture will enrichen with decrease in altitude. Had you need to do a go
around, the cruise mixture would have been sufficient for a full power
go-around.

Rick Durden wrote:
Otherwise, the only reason to enrichen the mixture during descent is
if the engine actually begins to run roughly. (See the POH which only
recommends enrichening if you experience engine roughness.) Most
people descend at 65% power or less, which means that it is impossible
to detonate the engine due to lack of heat and pressure, so it's
impossible to run it too lean (it will simply start to run rough and
then quit if you get it too lean, you won't hurt anything). Keeping
it leaned during descent helps avoid overcooling (if you believe in
shock cooling), helps keep the plugs from fouling and doesn't waste
fuel. In general, once you lean the engine for cruise on a T182 you
needn't touch the mixture control until you pull it to idle cutoff
after landing, or to go to full rich on a go around.

All the best,
Rick

The POH for my TB-21 (turbocharged Trinidad) with a
Lycoming TIO-540 calls for putting the mixture full rich
prior to landing. Is that different from what most people
do with this engine?

--
David Rind

I'll check my POH - I tend to enrichen somewhat by the fuel flow on the
Shadin - maybe this is a bad habit. I'm sure I'm not over 65% on the
descent.

Michael

"Rick Durden" wrote in message
m...
Michael,

What do you experience that causes you to have to enrichen your
mixture as you descend on your airplane? Are you descending while
carrying a very high power setting? I'm asking because I've flown
T182s and TR182s and have never run into a situation that required
enrichening the mixture during descent unless I leveled off at some
intermediate altitude and went to a relatively high power setting.

Otherwise, the only reason to enrichen the mixture during descent is
if the engine actually begins to run roughly. (See the POH which only
recommends enrichening if you experience engine roughness.)

Yes. The mixture was too rich.
This is a common problem with big-bore engines when operated
above 3000 MSL.

What we teach at Colorado Pilots Association is to set the
mixture to 15 GPH as you enter the pattern at (near) cruise
power. That way the engine continues to run on the ground. :-)

Of course, if you do a balked landing, you MUST push the mixture
full in after you increase the power for the go around.

Barry Klein wrote:
We took a newer 182 turbo to a 7000' elevation airport yesterday and
the engine quit at the end of the landing roll. I'm sure the mixture
was way too rich. It restarted without incident, glad we were on the
ground! We had the mixture set about 100 deg rich of peak TIT for
cruise at 9500. How should we have found the correct mixture setting
for power-off final approach, when the turbo is basically adding no
boost and we are at high density altitude? This is not addressed in
the POH. It does say full rich on takoff regardless of airport
elevation. Later that day, when taxiing for takoff, we set 1200 rpm
and leaned for peak rpm, mixture knob was out 1.5-2 inches to achieve
this.

When we returned home to 800' elevation, we checked the idle speed at
full rich, it was about 500 rpm, is this too low?


Thanks,
Barry


Best regards,

Jer/ "Flight instruction and mountain flying are my vocation!" Eberhard

--
Jer/ (Slash) Eberhard, Mountain Flying Aviation, LTD, Ft Collins, CO
CELL 970 231-6325 EMAIL jer'at'frii.com WEB http://www.frii.net/~jer
C-206 N9513G, CFII Airplane&Glider, FAA-DEN Aviation Safety Counselor
CAP-CO Mission&Aircraft CheckPilot, BM218 HAM N0FZD, 197 Young Eagles!

"David Rind" wrote in message
...
The POH for my TB-21 (turbocharged Trinidad) with a
Lycoming TIO-540 calls for putting the mixture full rich
prior to landing. Is that different from what most people
do with this engine?

What actual model engine does the TB-21 have? Just knowing that it's a
TIO-540 doesn't give us enough information to compare with our own engines.

The engine in my plane, a TIO-540-AA1AD, cannot stay running at full rich at
idle at high density altitudes, as I mentioned in another post. I put the
mixture to full rich before landing only when landing below 3000' or so (and
then only so that I am more prepared for a go-around...operationally, I wind
up leaning again after leaving the runway so that the plugs don't foul).

Pete

"Mark Mallory" wrote in message
...

Michael 182 wrote:
Really - my carbureted 182 calls for full rich on takeoff

So does mine - at SL on a standard day.

But not on a hot 95 degF afternoon at 5000 MSL.

What's the critical altitude of the turbocharged engine in your airplane?
Is it above or below the density altitude for that 95 F at 5000'?

As long as you are taking off at full power, I see no reason why you would
not use full rich mixture. Conversely, if even with the turbocharger, you
cannot make full power, I can believe one would need to lean.

I don't see why the difference should be between fuel-injected versus
carbureted. The metering is basically the same for both; only the method of
delivery is different.

Pete