3. Operation
Figure 2 shows the alternate air control lever in the cockpit. It is located on the left side of the center console under the instrument panel. A Bowden control cable connects the control lever in the cockpit to the alternate air valve assembly in the engine bay.
In normal operation the alternate air control lever is set to the OFF position. The holes in the alternate air valve body and the flanged housing do not align and ambient air flows through the air filter into the fuel injector.
When the alternate air control lever in the cockpit is moved to the alternate air position, the Bowden cable rotates the valve body to align the holes in the valve body with the holes in the flanged housing. Warm air from the engine bay will now flow through the alternate air valve into the fuel injector.
The alternate air valve can be selected to the alternate air position to supply warm air for anti-icing or to maintain the air supply should the air filter become blocked. The alternate air supply is not filtered.
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AIRCRAFT AMM
Cold Air
Stop Bush
Left Inner Wall of Floor Panel Pivot Lever
Bush
Adjusting Nuts Alternate Air Alternate Air Cable
Swivel Fitting
Figure 2: Alternate Air Control
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Trouble-Shooting
1. General
The table below lists the defects you could have with the air intake system. If you have the trouble detailed in the Trouble column read across to the Possible Cause column. Then do the repair given in the Repair column.
%

Trouble  Possible Cause  Repair 
Engine does not develop full power.  Air filter blocked/defective. Alternate air valve not closed. Alternate air control incorrectly set. Alternate air control cable broken.  Replace air filter. Set alternate air control to OFF. Do a test of the alternate air control adjustment. Adjust the alternate air control. Replace alternate air control cable. 

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Maintenance Practices
1. General
These maintenance practices tell you how to remove and install the air filter and the alternate air valve
assembly. They also tell you how to adjust, remove and install the alternate air control cable.
They do not tell you how to adjust the engine fuel injector.
Refer to the Lycoming Maintenance Manual for the data on the fuel injector.

2. Remove/Install the Air Filter
A. Remove the Air Filter
Detail Steps/Work Items  Key Items/References 
WARNING: DO NOT STAND WITHIN THE DANGER AREA OF THE PROPELLER IF THE ENGINE STARTS, THE PROPELLER CAN CAUSE DEATH OR INJURY TO PERSONS. WARNING: YOU MUST MAKE SURE THAT THE ENGINE IS SAFE BEFORE YOU DO WORK ON THE ENGINE CONTROLS. IF THE PROPELLER TURNS IT CAN CAUSE INJURY TO PERSONS. 
(1)  Make sure that the engine is safe: S Set the ignition switch to OFF. S Set the throttle control to IDLE. S Set the mixture control lever to LEAN CUT-OFF. 
(2)  Remove the engine cowlings.  Refer to Section 71-10. 
(3)  Disconnect the airplane battery.  Refer to Section 24-31. 
(4)  Loosen the worm-drive clamp that holds the air filter to air filter housing. 
(5)  Pull the air filter forward and clear of the air filter housing. 

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B. Install the Air Filter
Detail Steps/Work Items  Key Items/References 
　
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