SECTION 3
EMERGENCY PROCEDURES PA-28-181, ARCHER III
SECTION 3
EMERGENCY PROCEDURES PA-28-181, ARCHER III
REPORT: VB-1611 ISSUED: JULY 12, 1995
3-16
REPORT: VB-1611 ISSUED: JULY 12, 1995
3-16
3.33 CARBURETOR ICING
Under certain moist atmospheric conditions at temperatures of -5°C to
20°C, it is possible for ice to form in the induction system, even in summer
weather. This is due to the high air velocity through the carburetor venturi
and the absorption of heat from this air by vaporization of the fuel.
To avoid this, carburetor preheat is provided to replace the heat lost by
vaporization. Carburetor heat should be full on when carburetor ice is
encountered. Adjust mixture for maximum smoothness.
3.35 ENGINE ROUGHNESS
Engine roughness is usually due to carburetor icing which is indicated
by a drop in RPM, and may be accompanied by a slight loss of airspeed or
altitude. If too much ice is allowed to accumulate, restoration of full power
may not be possible; therefore, prompt action is required.
Turn carburetor heat on (See Note). RPM will decrease slightly and
roughness will increase. Wait for a decrease in engine roughness or an
increase in RPM, indicating ice removal. If no change in approximately one
minute, return the carburetor heat to OFF.
If the engine is still rough, adjust the mixture for maximum smoothness.
The engine will run rough if too rich or too lean. The electric fuel pump
should be switched to ON and the fuel selector switched to the other tank to
see if fuel contamination is the problem. Check the engine gauges for
abnormal readings. If any gauge readings are abnormal, proceed accord-
ingly. Select the Left magneto switch OFF then ON and repeat with the
Right magneto switch. If operation is satisfactory on either magneto, proceed
on that magneto at reduced power, with mixture full RICH, to a landing at
the first available airport.
If roughness persists, prepare for a precautionary landing at pilot’s
discretion.
NOTE
Partial carburetor heat may be worse than no
heat at all, since it may melt part of the ice,
which will refreeze in the intake system. When
using carburetor heat, therefore, always use full
heat, and when ice is removed return the con-
trol to the full cold position.
3.33 CARBURETOR ICING
Under certain moist atmospheric conditions at temperatures of -5°C to
20°C, it is possible for ice to form in the induction system, even in summer
weather. This is due to the high air velocity through the carburetor venturi
and the absorption of heat from this air by vaporization of the fuel.
To avoid this, carburetor preheat is provided to replace the heat lost by
vaporization. Carburetor heat should be full on when carburetor ice is
encountered. Adjust mixture for maximum smoothness.
3.35 ENGINE ROUGHNESS
Engine roughness is usually due to carburetor icing which is indicated
by a drop in RPM, and may be accompanied by a slight loss of airspeed or
altitude. If too much ice is allowed to accumulate, restoration of full power
may not be possible; therefore, prompt action is required.
Turn carburetor heat on (See Note). RPM will decrease slightly and
roughness will increase. Wait for a decrease in engine roughness or an
increase in RPM, indicating ice removal. If no change in approximately one
minute, return the carburetor heat to OFF.
If the engine is still rough, adjust the mixture for maximum smoothness.
The engine will run rough if too rich or too lean. The electric fuel pump
should be switched to ON and the fuel selector switched to the other tank to
see if fuel contamination is the problem. Check the engine gauges for
abnormal readings. If any gauge readings are abnormal, proceed accord-
ingly. Select the Left magneto switch OFF then ON and repeat with the
Right magneto switch. If operation is satisfactory on either magneto, proceed
on that magneto at reduced power, with mixture full RICH, to a landing at
the first available airport.
If roughness persists, prepare for a precautionary landing at pilot’s
discretion.
NOTE
Partial carburetor heat may be worse than no
heat at all, since it may melt part of the ice,
which will refreeze in the intake system. When
using carburetor heat, therefore, always use full
heat, and when ice is removed return the con-
trol to the full cold position.
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