COTTER PINS

Figure 2-57.—Types of cotter pins. AIRCRAFT SAFETYING METHODS Learning Objective: Identify the various safety methods used on aircraft hardware. You will come in contact with many different types of safetying materials. These materials are used to stop rotation and other movement of fasteners. They are also used to secure other equipment that may come loose due to vibration in the aircraft. COTTER PINS Cotter pins are used to secure bolts, screws, nuts, and pins. Some cotter pins are made of low-carbon steel, while others consist of stainless steel and are more resistant to corrosion. Also, stainless steel cotter pins may be used in locations where nonmagnetic material is required. Regardless of shape or material, all cotter pins are used for the same general purpose—safetying. Figure 2-57 shows three types of cotter pins and how their size is determined. NOTE: Whenever uneven prong cotter pins are used, the length measurement is to the end of the shortest prong. SAFETY WIRE Safety wire comes in many types and sizes. You must first select the correct type and size of wire for the job. Annealed corrosion-resistant wire is used in high-temperature, electrical equipment, and aircraft instrument applications. All nuts except the self-locking types must be safetied; the method used depends upon the particular installation. Figure 2-58 shows various methods commonly used in safety wiring nuts, bolts, and screws. Examples 1, 2, and 5 of figure 2-58 show the proper method of safety wiring bolts, screws, square head plugs, and similar parts when wired in pairs. Examples 6 and 7 show a single-threaded component wired to a housing or lug. Example 3 shows several components wired in series. Example 4 shows the proper method of wiring castellated nuts and studs. Note that there is no loop around the nut. Example 8 shows several components in a closely spaced, closed Figure 2-58.—Safety wiring methods. 2-45