A classic example of a control system is the negative feedback loop that controls the thermostat in your home. This loop, shown above in the block diagram, works continuously, many times a second, much more quickly and smoothly than a human pilot could. Turnbuckles A turnbuckle assembly is a mechanical screw device consisting of two threaded terminals and a threaded barrel.
Pulley wear patterns Fairleads may be made from a nonmetallic material, such as phenolic, or a metallic material, such as soft aluminum.
The above illustration shows how the basic elements of an autopilot system are related. When properly maintained, a tensiometer is 98 percent accurate.
Cable tension is determined by measuring the amount of force needed to make an offset in the cable between two hardened steel blocks called anvils. The cables run over pulleys, which are mounted on a bearing fastened to a structural member.
However, the grid method is sometimes used on large aircraft. The drawing shows a considerable redundancy of the flight control system: the inboard and outboard ailerons, elevators and rudder are controlled by both the primary and secondary computers and operated by the three hydraulic sub-systems; the high lift devices are controlled by their specific computers and operated by the three hydraulic systems Blue and Green for the leading edge,Yellow and Green for the trailing edge ; the vertical stabiliser, having a secondary role, is controlled only by the secondary computers and operated by two hydraulic sub-systems.
The unit consists of a compression spring and a locking mechanism that allows the spring to make correction in the system only when the cable system is in neutral.
These movements must be synchronized with the movement of the flight deck controls. The adjustments to the jacks necessary to level the aircraft are indicated on the grid scale. The thimble, bushing, and shackle fittings may be used in place of some types of terminal fittings when facilities and supplies are limited and immediate replacement of the cable is necessary.
Aircraft control cables are fabricated from carbon steel or stainless steel.