The 51 170A I bought has an EGT and Cyl head temp and carb heat temp gauge in it. When I was flying it home I noticed that the temps with no leaning were around 1150 to 1170 on the egt and around 250 on the cyl head temp, but I never looked that closely at the cyl head temps so don't quote me on that. When I leaned it out the egt would go to 1230 and was still climbing so I richened it up because I thought it was too hot. I coundn't really tell the difference with the tach and I don't have any experience with a mixture control(my 120 never had one). Can anyone enlighten me on how to do this? I am afraid of pulling the mixture control too far out and shutting down the engine. Maybe the probe is in the wrong spot? any info would be appreciated. I am a new owner of this aircraft so I will have some pretty stupid questions for a while so please forgive me in advance. I have a few more that I will save for another day when the forums are not seeing much action. Thanks for any replies.
Ken McCracken
51 170A
Fort McMurray AB
EGT temps and CYL head temps
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
C170A Temps
Ken,
According to my C170A flight manual the maximum temperatures are:
Max Oil Temp 225 F (107 C). Mine operates at about 210 F
Min Oil Temp for T/O 75 F
Max CHT 525 F (273 C). Mine operates at about 500 F (260 C)
EGT is used to lean the mixture at altitude. The actual temperature for peak EGT, and the amount of leaning, depends (primarily) on altitude.
To lean the mixture for cruise, set desired RPM (not above 75% power) then s l o o o w l y pull out (lean) the mixture control watching the EGT. The EGT will slowly rise (there is some lag between moving the control and the temp change showing on the gauge) until it peaks and will then start to fall again as you lean it further, RPM will start to drop and the engine run rough and/or lose power. Move the mixture control back in until you get peak EGT again and then richen it slightly (so EGT drops by 50 F is usually recommended, but the actual amount you use depends on how you want to operate your engine).
Redo this procedure each time you change power (RPM) or altitude.
The C170A Owner's Manual describes the method (similar to the above) for leaning the mixture without using an EGT.
Search through the previous topics on this forum - I am pretty sure there has been discussion on this (or similar) topic before.
I hope the above is of some assistance.
Regards
David
According to my C170A flight manual the maximum temperatures are:
Max Oil Temp 225 F (107 C). Mine operates at about 210 F
Min Oil Temp for T/O 75 F
Max CHT 525 F (273 C). Mine operates at about 500 F (260 C)
EGT is used to lean the mixture at altitude. The actual temperature for peak EGT, and the amount of leaning, depends (primarily) on altitude.
To lean the mixture for cruise, set desired RPM (not above 75% power) then s l o o o w l y pull out (lean) the mixture control watching the EGT. The EGT will slowly rise (there is some lag between moving the control and the temp change showing on the gauge) until it peaks and will then start to fall again as you lean it further, RPM will start to drop and the engine run rough and/or lose power. Move the mixture control back in until you get peak EGT again and then richen it slightly (so EGT drops by 50 F is usually recommended, but the actual amount you use depends on how you want to operate your engine).
Redo this procedure each time you change power (RPM) or altitude.
The C170A Owner's Manual describes the method (similar to the above) for leaning the mixture without using an EGT.
Search through the previous topics on this forum - I am pretty sure there has been discussion on this (or similar) topic before.
I hope the above is of some assistance.
Regards
David
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David Laseter
- Posts: 156
- Joined: Sun Oct 13, 2002 11:24 am
Leaning engine
Look at the 5th post under - Flying from Alaska to America.
gahorn explains how to lean the engine there, also.
Somewhere between Whitehorse and Watson Lk we had a moment. I kept checking to make sure I was leaned properly now and then. I'd pull the mixture control out till rough and push back in till smooth. Now all of a sudden, when I pushed back in, it went rough. That caught me off guard. I immediately pulled it out until it went rough again (lean) then started enriching again, this time I didn't get as far. And the mixture control was trapped with 1/4 inch of movement between lean and rich. I caught on and applied Carbheat and it nearly shutdown coughing until that ice was out of there. Anyway, that got me tuned up for the rest of the trip, at least concerning the Carb ice.
gahorn explains how to lean the engine there, also.
Somewhere between Whitehorse and Watson Lk we had a moment. I kept checking to make sure I was leaned properly now and then. I'd pull the mixture control out till rough and push back in till smooth. Now all of a sudden, when I pushed back in, it went rough. That caught me off guard. I immediately pulled it out until it went rough again (lean) then started enriching again, this time I didn't get as far. And the mixture control was trapped with 1/4 inch of movement between lean and rich. I caught on and applied Carbheat and it nearly shutdown coughing until that ice was out of there. Anyway, that got me tuned up for the rest of the trip, at least concerning the Carb ice.
Re: Leaning engine
Two weekends ago flying to Ozark, AR, there were airmets for turbulence below 10,000 feet. There was a temperature inversion down close to the ground. When I descended down to about 2,000 feet from 3,500 over Booneville giving up the tailwind from Dallas that I had been enjoying, the turbulence was uncomfortable. As I was bouncing around feeling uncomfortable, the engine started running rough.David Laseter wrote:Look at the 5th post under - Flying from Alaska to America.
gahorn explains how to lean the engine there, also.
Somewhere between Whitehorse and Watson Lk we had a moment. I kept checking to make sure I was leaned properly now and then. I'd pull the mixture control out till rough and push back in till smooth. Now all of a sudden, when I pushed back in, it went rough. That caught me off guard. I immediately pulled it out until it went rough again (lean) then started enriching again, this time I didn't get as far. And the mixture control was trapped with 1/4 inch of movement between lean and rich. I caught on and applied Carbheat and it nearly shutdown coughing until that ice was out of there. Anyway, that got me tuned up for the rest of the trip, at least concerning the Carb ice.
Much more uncomfort Immediately applied carb heat even though the RPM was at 2400 and the engine smoothed out. Ran fine all the way to Ozark, but it sure was a bad time to experience a rough engine. Gave rides the next day and then flew back to DFW with another tailwind after the front pushed thru. Point being, even with the engine running at 2400 RPM ( in the green ) carb ice happened.Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
Back when I was trying to tell Wilbur how to adjust bicycle spokes, carb ice probability was taught thusly:
Carb ice can occur at any power setting, at any altitude, and even in summertime temps. In fact, it's most likely to occur at temps above freezing. (If temps are well below freezing any moisture in the air is already frozen. The only way to get carb ice at that time (very unlikely) is if you use carb heat.)
Whenever you set power with a fixed pitch prop, make note of the rpm. If you see that rpm drop more than 50, assume it's due to carb ice and apply full carb heat to confirm and/or get rid of it. A big loss of rpm which recovers a little after a few seconds was carb ice. A big loss that just stays there was not. If carb ice continues to require frequent application of carb heat, then change altitude, or fly with heat constantly applied....re-leaning the engine to accomodate the overly rich mixture caused by the warm air.
Carb ice can occur at any power setting, at any altitude, and even in summertime temps. In fact, it's most likely to occur at temps above freezing. (If temps are well below freezing any moisture in the air is already frozen. The only way to get carb ice at that time (very unlikely) is if you use carb heat.)
Whenever you set power with a fixed pitch prop, make note of the rpm. If you see that rpm drop more than 50, assume it's due to carb ice and apply full carb heat to confirm and/or get rid of it. A big loss of rpm which recovers a little after a few seconds was carb ice. A big loss that just stays there was not. If carb ice continues to require frequent application of carb heat, then change altitude, or fly with heat constantly applied....re-leaning the engine to accomodate the overly rich mixture caused by the warm air.
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David Laseter
- Posts: 156
- Joined: Sun Oct 13, 2002 11:24 am
JOE, I sure wish I'd known you were coming to Ozark!
I'll PM you my phone number, and it will be in the 2003 directory for anyone else ( with a big H beside it).
Well thanks to ya'lls mentoring, I found a DIME size hole in my muffler shroud. Located beside were the duct goes to the carb heat. Wonder how long that's been there? I had my mechanics go over that plane just before we moved (40hrs ago).
Fixing to look at the complete Exhaust System. Even the Chrome Auto Tail Pipe Extensions are looking tacky now that we live in Civilization.
Sure wish I could join ya'll for the Fly-in - Christmas Party this weekend!
Still looking for my first fly-in!
Dave
I'll PM you my phone number, and it will be in the 2003 directory for anyone else ( with a big H beside it).
Well thanks to ya'lls mentoring, I found a DIME size hole in my muffler shroud. Located beside were the duct goes to the carb heat. Wonder how long that's been there? I had my mechanics go over that plane just before we moved (40hrs ago).
Fixing to look at the complete Exhaust System. Even the Chrome Auto Tail Pipe Extensions are looking tacky now that we live in Civilization.
Sure wish I could join ya'll for the Fly-in - Christmas Party this weekend!
Still looking for my first fly-in!
Dave
Dave, I had that - go see the relatives tunnel vision - on that trip and didn't think about other opportunities. You know how many relatives us people from Arkansas have, everyone in town 
.
Been thinking about exploring some airports in Southeast Oklahoma that have camping available. Suppose to be a great weekend weather wise, let me know if you would be interested in meeting in that area. It would be about an hours flight for both of us.
.Been thinking about exploring some airports in Southeast Oklahoma that have camping available. Suppose to be a great weekend weather wise, let me know if you would be interested in meeting in that area. It would be about an hours flight for both of us.
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
Carby Icing
Page 11 of the pdf document
http://www.casa.gov.au/avreg/pilot/down ... FLIGHT.pdf
contains a chart showing the likelyhood of the formation of carby icing.
As you can see, carby icing can occur in conditions of relative humidity greater than 20% and temperatures from about -5* C (23* F) to higher than 35* C (95* F).
Be alert (your country needs more lerts
)
[The above document is part of the "VFR Flight Guide" published by the Civil Aviation Safety Authority (of Australia) - our version of the FAA. This document contains all the rules and regulations affecting VFR flights, in relatively plain language, and is a very handy reference for this information.]
David
http://www.casa.gov.au/avreg/pilot/down ... FLIGHT.pdf
contains a chart showing the likelyhood of the formation of carby icing.
As you can see, carby icing can occur in conditions of relative humidity greater than 20% and temperatures from about -5* C (23* F) to higher than 35* C (95* F).
Be alert (your country needs more lerts
)[The above document is part of the "VFR Flight Guide" published by the Civil Aviation Safety Authority (of Australia) - our version of the FAA. This document contains all the rules and regulations affecting VFR flights, in relatively plain language, and is a very handy reference for this information.]
David
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David Laseter
- Posts: 156
- Joined: Sun Oct 13, 2002 11:24 am
Carburetor Temperature Guage
When the needle is in the yellow zone, conditions are favorable for carburetor icing.
Where is the temp probe located?
Is the gauge indicating temp AND humidity in the atmosphere?
Or is it indicating conditions right at the Carburetor throat?
I've basically viewed it as a warning and pay special attention to monitoring the manifold pressure gauge and rpm's for loss of power before applying full carb heat?
How do I best utilize this gauge?
When the needle is in the yellow zone, conditions are favorable for carburetor icing.
Where is the temp probe located?
Is the gauge indicating temp AND humidity in the atmosphere?
Or is it indicating conditions right at the Carburetor throat?
I've basically viewed it as a warning and pay special attention to monitoring the manifold pressure gauge and rpm's for loss of power before applying full carb heat?
How do I best utilize this gauge?
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Bill Venohr
- Posts: 90
- Joined: Tue Apr 23, 2002 1:42 pm
Dave--my 170 is the first plane I've flown with a carb temperature gauge. In 3 years of ownership I've had a number of times with carb ice, and every time the temperature was in the yellow. So anytime the temp is in or near the yellow I'm even more vigilant.
As a side note, from my limited experience it seems my 170 is more susceptible to carb ice than any other carbureted planes I've flown. Any thoughts?
As a side note, from my limited experience it seems my 170 is more susceptible to carb ice than any other carbureted planes I've flown. Any thoughts?
Bill Venohr
N4044V
Aurora, CO
N4044V
Aurora, CO
The O-300/O-200 Continentals carb's do not benefit as much from sump heat absorption as some other designs, so they do have a reputation for being more susceptible.
The carb temp probe is mounted in the carb throat and measures carb "body" temperature. When the carb is operating in an ambient temp and fuel flow condition such that the rate of evaporating gasoline chills the carb-body to below freezing then any moisture/humidity can freeze. The carb temp probe knows nothing of actual ice or humidity. It's primary use is to assist in using only the least amount of carb heat necessary to keep the carb above ice-formation temps. (You don't have to suffer quite as much performance loss if you don't have to create quite as much hot-air suction thru the carb heat system.) It is NOT for the purpose of actually detecting ice, and for my 2 cents, is dead weight in a 170. (It's pretty useful in a Martin 202, though. In fact, TWA pioneered the use of that gauge when they insisted upon them being installed in the 202's and altered their checklists assigning the co-pilot the task of continuous monitoring the carb heat/carb temp. The only other significant tasks he had was to read the checklist, load/unload baggage, and be the Captain's sexual-advisor. "When I want your F---ing advice...I'll ASK for it! )
The carb temp probe is mounted in the carb throat and measures carb "body" temperature. When the carb is operating in an ambient temp and fuel flow condition such that the rate of evaporating gasoline chills the carb-body to below freezing then any moisture/humidity can freeze. The carb temp probe knows nothing of actual ice or humidity. It's primary use is to assist in using only the least amount of carb heat necessary to keep the carb above ice-formation temps. (You don't have to suffer quite as much performance loss if you don't have to create quite as much hot-air suction thru the carb heat system.) It is NOT for the purpose of actually detecting ice, and for my 2 cents, is dead weight in a 170. (It's pretty useful in a Martin 202, though. In fact, TWA pioneered the use of that gauge when they insisted upon them being installed in the 202's and altered their checklists assigning the co-pilot the task of continuous monitoring the carb heat/carb temp. The only other significant tasks he had was to read the checklist, load/unload baggage, and be the Captain's sexual-advisor. "When I want your F---ing advice...I'll ASK for it!
)All the discussion concerning carburetor ice is interesting. In all of the years that I've flown my airplane in all kinds of atmospheric conditions I don't ever recall getting even a hint of carburetor ice. I've often used the carburetor heat to check it for ice, but I don't ever remember getting the slightest indication that any ice had formed. I am, of course,
referring to the time when I had the old Cintinental C-145
engine installed. The new IO-360, being fuel injected, does
not ice.
My old Stinson L-5 with a lycoming O-435-11 would clog up on clear summer days if the relative humidity was up at all.
referring to the time when I had the old Cintinental C-145
engine installed. The new IO-360, being fuel injected, does
not ice.
My old Stinson L-5 with a lycoming O-435-11 would clog up on clear summer days if the relative humidity was up at all.
BL
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David Laseter
- Posts: 156
- Joined: Sun Oct 13, 2002 11:24 am
I understand George!Except the part about being dead weight. The more gauges and gatchets I have on the panel, the more complicated it looks to my passengers. Only problem is when they ask me to explain
So, if the needle is in the yellow and I suspect carb icing @ RPM drop or MP drop, then I pull the Carb Heat out, but only as far as needed to get the needle out of the yellow zone? Partial carburetor heat. Which is normally very dangerous because of the chance of warming a super-cold venturi and supercooled ice crystals, thus forming ice in the Carb. But since I can read the temp of the Carb body, then I can apply partial Carb Heat ( Re-leaning because of less-dense air ) and not have as drastic of a power loss as when Full Carb Heat is applied.
I bet I get some cautions over this!
When selecting carb heat, always apply FULL HEAT....observe the total rpm drop, and wait to see if any of that drop recovers as ice is melted out. If no recovery occurs....if the first amount of drop remains there....then you had no carb ice.
The carb temp gauge is only used to keep the carb air temp within a range to prevent ice....not remove it. To keep the air temp in such a range may require partial carb heat on a conitinuous basis (with the result of continuous reduction of available power.)
See what I mean now, when I say a carb temp gauge is dead weight? It will not do you a single bit of good to detect carb ice. It will only enable (and encourage) someone to fly around fiddling with partial carb heat, which will sooner or later get you into trouble.
The carb temp gauge is only used to keep the carb air temp within a range to prevent ice....not remove it. To keep the air temp in such a range may require partial carb heat on a conitinuous basis (with the result of continuous reduction of available power.)
See what I mean now, when I say a carb temp gauge is dead weight? It will not do you a single bit of good to detect carb ice. It will only enable (and encourage) someone to fly around fiddling with partial carb heat, which will sooner or later get you into trouble.
Back when I used to flight instruct a lot, the 150's we used were unpredictable about carb ice. We got ice one day, and not the next. We'd get students back from cross country trips shaking and telling horror stories about how the engine got rough and tried to quit on them (and they had all kinds of theories about why, ......taking lots of convincing them about carb heat usage. Funny thing, tho', ....those same guys never had a "bad engine" story after they started using carb heat properly by forming a good habit of monitoring rpm in cruise.)blueldr wrote:All the discussion concerning carburetor ice is interesting. In all of the years that I've flown my airplane in all kinds of atmospheric conditions I don't ever recall getting even a hint of carburetor ice. I've often used the carburetor heat to check it for ice, but I don't ever remember getting the slightest indication that any ice had formed. I am, of course,
referring to the time when I had the old Cintinental C-145
engine installed. The new IO-360, being fuel injected, does
not ice.
My old Stinson L-5 with a lycoming O-435-11 would clog up on clear summer days if the relative humidity was up at all.
Anyway, ....I also recall the O-300 172's we had, occasionally picking up a load of it. But this 170B I have has never made any yet (in the 4 years that I've owned it.) I just put lots of cycles on the heat knob, tho'. I pull it full on before reducing power out of the green for any descent. I also apply it full on if I notice any rpm drop from any selected power setting. If I don't experience any ice (recovered rpm) then I put it back off, ...but that's not what we taught less-experienced pilots. We always insisted they leave it on whenever below the green arc.