Recommendations
There are some steps a pilot can take to prevent, recognize,
and respond to carburetor icing.
To prevent carburetor icing, the pilot should:
• Assure the proper functionality of the carburetor heat
during the ground check (before takeoff).
• Use carburetor heat on approach and descent when
operating at low power settings, or in conditions where
carburetor icing is probable.
To recognize carburetor icing, the warning
signs are:
• A drop in rpm in fixed-pitch propeller airplanes.
• A drop in manifold pressure in constant-speed
propeller airplanes.
• In both types, usually there will be rough engine
operation.
The pilot should respond to carburetor icing by
applying full carburetor heat immediately. The engine
may run rough initially for a short time while the ice
melts. The recommendations are general suggestions.
The pilot should consult the AFM or the pilot’s operating
handbook for the proper use of carburetor heat.
The references below, and their associated links,
provide more information:
• AC 20-113, Pilot Precautions and Procedures to
be Taken in Preventing Aircraft Reciprocating Engine
Induction System and Fuel System Icing Problems
http://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgAdvisoryCircular.nsf/0/F5BD7904845409D862569AE0
0783347?OpenDocument&Highlight=carburetor%20icing.
• AC 91-51A, Effect of Icing on Aircraft Control and
Airplane Deice and Anti-Ice Systems
http://rgl.FAA.gov/Regulatory_and_Guidance_Library/
rgAdvisoryCircular.nsf/0/451296DBDF212C81862569E70
077C8F9?OpenDocument&Highlight=carburetor%icing
• AOPA Safety Advisor—Aircraft Icing
www.AOPA.org/asf/publications/sa11.pdf
• AOPA Safety Advisor—Aircraft Deicing and Anti-
icing Equipment
www.AOPA.org/asf/publications/sa22.pdf
For more information contact Peter L. Rouse, aerospace
engineer, Small Airplane Directorate, at 816-329-4135
or e-mail peter.rouse@faa.gov.
