Rig pins are used in rigging control systems. Figure 9-24 shows a rigging pin kit used on one of the Navys aircraft. As you can see, rig pins may come in various sizes and shapes and may be designed for one or many installations. You should refer to the specific maintenance instructions manual for use and selection of rig pins.

Throwboards are special equipment used on specific aircraft for accurate measurement of control surface travel. See figure 9-25. Each throwboard has a protractor scale that indicates a range of travel in degrees. Zero degrees normally indicates the neutral position of the control surface. When the throwboard is mounted and the control column or stick is in neutral, the trailing edge of the control surface should be aligned to zero. As the control column or stick is moved to its extreme limits, you can read the corresponding degree indication on the throwboard. If the travel of the control surface is out of limits, you should adjust cables, push-pull rods, and control limit stops to obtain the correct control surface travel. When you are inspecting and rigging control surfaces, the specific maintenance instructions manual should be consulted.

Figure 9-25.Typical throwboard used for rigging rudder and rudder tab controls.



Figure 9-26.Typical elevator flight control system.