33 votes
Accepted

C-152 carb heat on before landing in hot weather?

You should always pull the carb heat when throttling back no matter the conditions for 3 reasons: Ice forms from moisture (duh!), and there's much more moisture in hot tropical air than cold arctic ...
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19 votes

C-152 carb heat on before landing in hot weather?

Carb heat use is not related to OAT, it's related to moisture and how it can turn to ice in the carb, causing the engine to stop. Carb ice can form at any outside air temperature, which is why you ...
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  • 11.2k
19 votes
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Why does using carburetor heat increase fuel consumption?

I can think of two reasons: The efficiency of heat machines depends on the difference between lowest and highest temperature in the cycle, relative to the highest temperature, as formulated first by ...
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11 votes

C-152 carb heat on before landing in hot weather?

You have mentioned OAT, but remember there are 2 variables for potential icing - the other being Dew Point. You (roughly) 85F OAT could easily fall into Serious Icing at glide power for a wide range ...
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8 votes

Why does using carburetor heat increase fuel consumption?

Heating the air causes the air to be less dense. We all know that as you climb, the air becomes less dense and you have to lean the mixture for better performance and fuel economy. This also applies ...
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6 votes

C-152 carb heat on before landing in hot weather?

Thou shalt use Carb Heat. You said you fly in tropical area where the temperature is 30°C. Warm tropical air has a lot of moisture as others have mentioned. The venturi effect can drop the air ...
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5 votes

Why do we check Idle operation with carb heat on during a Cessna 172 run-up?

Because, in engaging the carburetor heat, you are decreasing the density of the air entering the engine with the same fuel flow, thereby richening the mixture. At idle power, if the throttle idle set ...
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4 votes

C-152 carb heat on before landing in hot weather?

Most of the temperature drop is from fuel evaporation downstream of the venturi, causing ice from ambient humidity to form on the throttle plate (injected engines also have venturis and throttle ...
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3 votes
Accepted

Why does engine temperature rise upon applying carburetor heat?

Switching Carb Heat to ON sends air to the carburetor that was heated by being near the exhaust pipe. While it is correct the fuel/air mixture will be richer, the amount of fuel entering the engine ...
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2 votes

Why do we check Idle operation with carb heat on during a Cessna 172 run-up?

Carlo Felicione has given a great explanation of why carb heat at idle would need to be checked. The incoming air heated by the exhaust manifold would be less dense than the incoming air without carb ...
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2 votes

Carburetor Heat Required on Carburetor equipped GA aircraft?

Carb heat is not specifically required by regulation. What is required by the following rule is a means to prevent ice accretion: 14 CFR 33.35 Fuel and induction system. (b) The intake ...
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1 vote
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Carb Heat and Lycoming Engines

It's because the spider duct that connects the carb to the intake runners going to the cylinders is cast into the oil sump and the carb mounts directly to that. So the carb gets a lot of engine heat ...
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