CABLE CONTROL SYSTEM

General: The conventional cable control system consists of flexible cable, terminals (end fittings) for attaching to other units, and turnbuckles.

primary flight control systems. Cable-type linkage is also used in engine controls, emergency extension systems for the landing gear, and various other systems throughout the aircraft.
Cable-type linkage has several advantages over the other types. It is strong and light in weight, and its flexibility makes it easy to route through the aircraft. An aircraft cable has a high mechanical efficiency and can be set up without backlash, which is very important for precise control.
Cable linkage also has some disadvantages. Tension must be adjusted frequently due to stretching and temperature changes.

Aircraft control cables are fabricated from carbon steel or stainless steel.
The basic component of a cable is a wire. The diameter of the wire determines the total diameter of the cable. A number of wires are preformed into a helical or spiral shape and then formed into a strand. These preformed strands are laid around a straight center strand to form a cable.
Cable designations are based on the number of strands and the number of wires in each strand. The most common aircraft cables are the 7 X 7 and 7 X 19.

The 7 X 7 cable consists of seven strands of seven wires each. Six of these strands are laid around the center strand (see figure 3.1).This is a cable of medium flexibility and is used for trim tab controls, engine controls, and indicator controls.

The 7 X 19 cable is made up of seven strands of 19 wires each. Six of these strands are laid around the center strand (see figure 3.1). This cable is extra flexible and is used in primary control systems and in other places where operation over pulleys is frequent.
Aircraft control cables vary in diameter, ranging from K6 to Y8 inch. The diameter is measured as shown in figure 3.1. 

Figure 3.1: Cable cross sections