Open Door; Carburetor Icing; Engine Roughness - Piper Cherokee Archer II Operating Handbook

Piper Aircraft Corporation
PA-28-181, Cherokee Archer II

3.14 OPEN DOOR

The cabin door on the Cherokee is double latched, so the chances of its springing open in flight at both the
top and side are remote. However, should you forget the upper latch, or not fully engage the side latch,
the door may spring partially open. This will usually happen at takeoff or soon afterward. A partially
open door will not affect normal flight characteristics, and a normal landing can be made with the door
open.
If both upper and side latches are open, the door will trail slightly open, and airspeed will be reduced
slightly.
To close the door in flight, slow the airplane to 87 KIAS, close the cabin vents and open the storm
window. If the top latch is open, latch it. If the side latch is open, pull on the armrest while moving the
latch handle to the latched position. If both latches are open, close the side latch then the top latch.

3.15 CARBURETOR ICING

Under certain moist atmospheric conditions at temperatures of -5 to 20 degrees 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 venture 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.

3.16 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 accordingly. Move the magneto switch to "L" then to "R,"
then back the "BOTH." 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 control to the full cold position.
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