A B C D E F G H J K A B C D E F G H J K Serrated throttle control arm Control rod Adjustable rod ends Cable drum Tensiometer Cushion movement Quadrant locking pin Cable turnbuckle Cable drum locking pin Throttle stop Figure 8-11.  Schematic drawing of throttle control system.  Next, adjust the throttle control so that it has a slight cushion  action at two positions on the throttle quadrant: one when  the carburetor throttle valve is in the full-open position and  the other when it is closed to the idle position (stop to stop). Adjust the cushion by turning the cable turnbuckles equally  in opposite directions until the throttle control cushion is  correct at the full-open position of the throttle valve. Then,  when the throttle arm stop is adjusted to the correct idle speed  setting, the amount of cushion should be within tolerance at  the idle speed position of the throttle valve. The presence of  this cushion ensures that the travel of the throttle valve is not  limited by the stops on the throttle control quadrant, but that  they are opening fully and closing to the correct idle speed  as determined by the throttle arm stop. Adjustment of the engine controls is basically the same on all  aircraft regarding the linkage adjustment to a predetermined  length for a specific setting of the unit to be controlled. Then  adjust cables, if used in the control system, to a specific  tension with the control system locked. Finally, the full  travel of the unit to be controlled is ensured by establishing  the correct cushion in the controls. In general, the same basic  procedure is used to connect the linkage of the remaining  engine controls. After rigging the engine controls, safety the  turnbuckles and castle nuts, and make certain the jam nuts  on all control rods are tightened. On multiengine aircraft, the amount of cushion of all engine  controls on each quadrant must be equal so that all are  aligned at any specific setting chosen. This eliminates the  necessity of setting each control individually to synchronize  engine operations. After the engine has been installed, it is necessary to adjust  the cowl flaps, if installed, so that the passage of the cooling  air over the engine can be regulated accurately. Operate the  system and recheck for opening and closing to the specified  limits. Also, check the cowl flap position indicators, if  installed, to ensure that they indicate the true position of the  cowl flaps. Cowl flaps are doors at the bottom of the rear  cowling that are used to control air flow through the cowling.  8-12