assemblies are coupled by means of a coupling nut. Each consists of an aluminum shell containing an insulating insert that holds the current-carrying contacts. The plug is usually attached to the cable end, and is the part of the connector on which the coupling nut is mounted. The receptacle is the half of the connector to which the plug is connected. It is usually mounted on a part of the equipment. One type of connector commonly used in aircraft electrical systems is shown in figure 5-19. TERMINALS Since most aircraft wires are stranded, it is necessary to use terminal lugs to hold the strands together. This allows a means of fastening the wires to terminal studs. The terminals used in electrical wiring are either of the soldered or crimped type. Terminals used in repair work must be of the size and type specified in the applicable maintenance instruction manual. The crimped-type terminals are generally recommended for use on naval aircraft. Soldered-type terminals are usually used in emergencies only. The basic types of solderless terminals are shown in figure 5-20. They are the straight, right angle, flag, and splice types. There are variations of these types. BONDING When you connect all the metal parts of an aircraft to complete an electrical unit, it is called bonding. Bonding connections are made of screws, nuts, washers, clamps, and bonding jumpers. Figure 5-21 shows a typical bonding link installation. An aircraft can become highly charged with static electricity while in flight. If the aircraft is improperly bonded, all metal parts do not have the same amount of static charge. A difference of potential exists between the various metal surfaces. If the resistance between insulated metal surfaces is great enough, charges can accumulate. The potential difference could become high enough to cause a spark. This constitutes a fire hazard and also causes radio interference. If lighting strikes an aircraft, a good conducting path for heavy current is necessary to minimize severe arcing and sparks. Bonding also provides the necessary low- resistance return path for single-wire electrical systems. This low-resistance path provides a means of bringing the entire aircraft to the earth's potential when it is grounded. 5-14 ANF0519 RECEPTACLE ASSEMBLY COUPLING NUT PLUG SOCKET ASSEMBLY Figure 5-19.—Connector assembly. ANF0520 TOUGUE BARREL TERMINAL HOLE STRAIGHT RIGHT ANGLE FLAG SPLICE Figure 5-20.—Basic types of solderless terminals. ANF0521 Figure 5-21.—Typical bonding link installation.