A carb heat trick
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Interesting leaflet. My experience does not lead me to agree with all of it, but it's generally good.
I'm opposed to the notion of procedurally fiddling with carb heat at 200' feet up on final. This is the phase of flight when minimizing "things to do" in the cockpit is good. Rather that pre configuring the aircraft for a slight chance go around, why not leave it configured as described in the POH, and only reselect carb heat on that very infrequent occasion when a go around might be required, you'll have time... The plane will go around with carb heat hot if it has to, and once you have your focus on flying the overshoot, then you can come back to the engine controls!
I'm opposed to the notion of procedurally fiddling with carb heat at 200' feet up on final. This is the phase of flight when minimizing "things to do" in the cockpit is good. Rather that pre configuring the aircraft for a slight chance go around, why not leave it configured as described in the POH, and only reselect carb heat on that very infrequent occasion when a go around might be required, you'll have time... The plane will go around with carb heat hot if it has to, and once you have your focus on flying the overshoot, then you can come back to the engine controls!
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I'm opposed to the notion of procedurally fiddling with carb heat at 200' feet up on final. This is the phase of flight when minimizing "things to do" in the cockpit is good. Rather that pre configuring the aircraft for a slight chance go around, why not leave it configured as described in the POH, and only reselect carb heat on that very infrequent occasion when a go around might be required, you'll have time... The plane will go around with carb heat hot if it has to, and once you have your focus on flying the overshoot, then you can come back to the engine controls!
From Leaflet 14
Unless otherwise stated in the Pilot's
Operating Handbook or Flight
Manual, the HOT position should be
selected well before power is reduced
and retained to touchdown. On some
engine installations, to ensure better
engine response and to permit a
go-around to be initiated without
delay, it may be recommended that
the carb hot air be returned to COLD
at about 200/300 ft on finals.
m) Go-around or Touch and Go
The leaflet clearly says for carb heat to stay on until touchdown unless the POH specifically requires the carb heat off. Every carburated single engine Cessna POH says carb heat on for landing.
Some Pipers do have a note in the POH that cautions that "carb heat should not be on for approach and landing unless icing conditions are present"
Having carb heat on until 200 feet as a general practice regardless of conditions would be operating contrary to the POH. In any case if you have the carb heat on during an approach in a Piper because you are experiencing icing, it seems pretty silly to turn it off when you are still in the air.
Grumman POH's have a note in the before landing checklist that says "Carb Heat: As required, leave on if icing conditions exist"
Unless otherwise stated in the Pilot's
Operating Handbook or Flight
Manual, the HOT position should be
selected well before power is reduced
and retained to touchdown. On some
engine installations, to ensure better
engine response and to permit a
go-around to be initiated without
delay, it may be recommended that
the carb hot air be returned to COLD
at about 200/300 ft on finals.
m) Go-around or Touch and Go
The leaflet clearly says for carb heat to stay on until touchdown unless the POH specifically requires the carb heat off. Every carburated single engine Cessna POH says carb heat on for landing.
Some Pipers do have a note in the POH that cautions that "carb heat should not be on for approach and landing unless icing conditions are present"
Having carb heat on until 200 feet as a general practice regardless of conditions would be operating contrary to the POH. In any case if you have the carb heat on during an approach in a Piper because you are experiencing icing, it seems pretty silly to turn it off when you are still in the air.
Grumman POH's have a note in the before landing checklist that says "Carb Heat: As required, leave on if icing conditions exist"
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The efficiency of the carb heat system will be indicated by the magnitude of the RPM drop during the runup. I have grounded several airplanes when they did not IMO appear to be getting sufficient heated air during the runup carb heat check as indicated by a non existent or very small drop in RPM when the carb heat was selected full on. In all cases various problems were found with cracked carb air boxes, deteriorated scat hoses or improperly adjusted carb heat controls.
During the carb heat check on the run up there was barely any needle movement. I ended up calling the instructor who checked me out and he assured me that it is normal. The owner of the school who seems to be very knowledgeable later said the same. He said that the heater unit around the exhaust pipe is smaller than the Cessna's I am used to.
I have meant to ask about this on a Grumman forum but haven't done so yet. No problems encountered on that flight.
I rent a Grumman Cheetah in Dallas. Recently I flew one of their models that I had not flown before. It had been several months since my last flight and I only have a few flights total.
During the carb heat check on the run up there was barely any needle movement. I ended up calling the instructor who checked me out and he assured me that it is normal. The owner of the school who seems to be very knowledgeable later said the same. He said that the heater unit around the exhaust pipe is smaller than the Cessna's I am used to.
I have meant to ask about this on a Grumman forum but haven't done so yet. No problems encountered on that flight.
During the carb heat check on the run up there was barely any needle movement. I ended up calling the instructor who checked me out and he assured me that it is normal. The owner of the school who seems to be very knowledgeable later said the same. He said that the heater unit around the exhaust pipe is smaller than the Cessna's I am used to.
I have meant to ask about this on a Grumman forum but haven't done so yet. No problems encountered on that flight.
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Returning carb air to cold at 200 feet is a stupid dangerous folk lore procedure started by Cherokee instructors 50 years ago and passed on without question. A small amount of dust in the carburetor wont kill you, carburetor icing can, as accidents show.
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Life does not necessarily end when the fan stops turning... You just enter the fascinating realm of 'Gliding'.
If you are flying from one of the ex WW2 airfields, at 200ft you most likely have 1/4 to 1/2 mile of Paved Undershoot underneath you.
''Keep Calm and Stay Flying''
If you are flying from one of the ex WW2 airfields, at 200ft you most likely have 1/4 to 1/2 mile of Paved Undershoot underneath you.
''Keep Calm and Stay Flying''
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Can anyone quote me the power loss for full power with carb. heat on?
But I'm not saying that's appropriate data for each engine model....
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Thanks for the info BPF. I was told that all the Cheetahs in this flight school are the same. While I do see that you have Grumman experience, it isn't on the Cheetah. Is it possible that there could be a difference. Any Cheetah pilots out there.
Some Pipers do have a note in the POH that cautions that "carb heat should not be on for approach and landing unless icing conditions are present"
This is a good report to read concerning carb icing:-
The investigation did not find any evidence of a failure within the engine but the atmospheric conditions were conducive to carburettor icing.
If you conduct a straight in/direct approach you invariably won't fly downwind! For this reason when teaching I always refer to them as (Pre) Landing Checks. As the report above shows the practice of selecting hot air in the pre landing checks won't necessarily give you the protection you need. You need to select hot before reducing power for the approach and leave it there until landing and/or going around.
The investigation did not find any evidence of a failure within the engine but the atmospheric conditions were conducive to carburettor icing.
Each of the local training establishments that I have knowledge of, all say that there are three times when you should apply carb heat... 1. If you think carb icing is likely. 2. Any time the engine is run below 2000rpm. and 3. As the C in the downwind pre-landing BUMFFPITCHH checks.
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Re BPF 'This switching off of Carb heat on short final seems to be a unique to British flight training practice that seems to have been mindlessly passed down through the generations. 
'
I got my licence on the Australian syllabus and was taught to keep carb heat on until on the ground. When I converted my licence to a UK one, I was told to switch carb hear off at 200'. I've since seen this requirement documented in the order book of a flying club.
'I got my licence on the Australian syllabus and was taught to keep carb heat on until on the ground. When I converted my licence to a UK one, I was told to switch carb hear off at 200'. I've since seen this requirement documented in the order book of a flying club.
I've flown a couple of Cheetahs.
The carb heat drop on runup (from memory, this was a while back) was quite small. Maybe 50-100 revs.
Try it aloft at cruise power. I did, and the difference was more noticeable.
The carb heat drop on runup (from memory, this was a while back) was quite small. Maybe 50-100 revs.
Try it aloft at cruise power. I did, and the difference was more noticeable.
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Always worth reading other peoples experiences, i think that discussions on carb heat should be always at the fore, where do you think it stands in the list of accident causes? how long do you do a carb heat check for? 5 seconds? 20 seconds?
I learned to fly in the 1970s on a Continental powered taildragger. I was taught then to leave carb heat on from downwind right through to touchdown. Later, converting to Lycoming powered PA28s they told me to apply carb heat briefly on downwind and then to go to cold for the rest of the circuit and landing. In the light of all the above posts, this advise would have seemed to be very unwise!
I think previous posters are right that some advise seems to be handed down over the years without any re analysis from experience.
Nowadays, flying mainly Cessna 172, I frequently notice icing right after engine start and need carb heat during the first part of the initial warm up.
I think previous posters are right that some advise seems to be handed down over the years without any re analysis from experience.
Nowadays, flying mainly Cessna 172, I frequently notice icing right after engine start and need carb heat during the first part of the initial warm up.
Without reading back over the older years:-
At a dusty or grit covered landing strip, carb. air 'cold' ensures the engine gets filtered air. Whereas 'Carb. heat' bypasses all such protection -
So perhaps it's a case for having more power for going around combined with helping preserve the engine innards. Particularly on circuit bashing/training a/c?
mikehallam.
At a dusty or grit covered landing strip, carb. air 'cold' ensures the engine gets filtered air. Whereas 'Carb. heat' bypasses all such protection -
So perhaps it's a case for having more power for going around combined with helping preserve the engine innards. Particularly on circuit bashing/training a/c?
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I may be wrong but just how much lack of power results from carb heat on versus off?
My Emeraude with its Continental C90 (apparently ice making machine) drops about 20/30 revs with it on, possibly less than that, I can barely see much movement on the dial.
It climbs out over trees on the 600 metre strip, no problem with carb hot, full flap, and over weight.
So I am in no hurry to blindly follow old wives tales passed down over years of " that's the way I was taught".
Yes the carb heat does work because I once picked up ice while taxiing on wet grass, carb cold, it was cleared in a few minutes using hot.
Perhaps this depends on the airframe/engine setup?
My Emeraude with its Continental C90 (apparently ice making machine) drops about 20/30 revs with it on, possibly less than that, I can barely see much movement on the dial.
It climbs out over trees on the 600 metre strip, no problem with carb hot, full flap, and over weight.
So I am in no hurry to blindly follow old wives tales passed down over years of " that's the way I was taught".
Yes the carb heat does work because I once picked up ice while taxiing on wet grass, carb cold, it was cleared in a few minutes using hot.
Perhaps this depends on the airframe/engine setup?
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I get only about a 50 rpm drop on applying carb heat during the run up - used to get about 200 in 172's.
I too have one those carb heat gauges with the small yellow avoid area in which the needle always seems to obstinately remain embedded.
Things would have to get quite desperate for the extra heat of leaning to have an effect - but if all else fails, why not - as the TV ad says "every little helps".
I too have one those carb heat gauges with the small yellow avoid area in which the needle always seems to obstinately remain embedded.
Things would have to get quite desperate for the extra heat of leaning to have an effect - but if all else fails, why not - as the TV ad says "every little helps".