CORRECT!

7). Which condition is most favorable to the development of carburetor icing?

a). Temperature between 20 and 70° F and high humidity.
b). Temperature between 32 and 50° F and low humidity.
c). Any temperature below freezing and a relative humidity of less than 50 percent.
The answer is:
a). Temperature between 20 and 70° F and high humidity.

The real key to this answer is 'high humidity'. Carb ice usually will not form when the air coming in to the carburetor contains low amounts of moisture. That being said, mis-management of the carb heat system (using partial heat intermittently, for example, when the POH states to use full carb heat for a specified amount of time) can actually increase the chances for carb ice formation by heating the incoming air to an appropriate temperature to allow negligible amounts of moisture to condense and form ice on the inside of the carb's venturi. Always refer to the POH for manufacturer's recommendations on any system.

Also, don't be fooled into thinking that, just because it is a nice warm day, carb ice cannot be the reason for that suddenly rough-running engine. If the engine starts to run rough, follow the recommended emergency procedure checklist found in the POH. I'm sure that one of the steps will be to apply carb heat (if the engine is so equipped).

Really cold air masses usually can't hold enough moisture to result in carb ice (but remember: the weather isn't always 100% predictable. Just ask any meteorologist or winds-aloft forecaster...).

back