1½" (approx.) 1½" (approx.) Step 1 Step 2 Step 4 Step 5 Step 3 4-62 Terminal blocks are normally supplied with studs secured  in place by a plain washer, an external tooth lockwasher,  and a nut. In connecting terminals, a recommended practice  is to place copper terminal jugs directly on top of the nut,  followed with a plain washer and elastic stop nut, or with a  plain washer, split steel lockwasher, and plain nut. Terminal lugs should be installed on terminal blocks in such a  manner that they are locked against movement in the direction  of loosening.  [Figure 4-109] Bonding is the electrical connecting of two or more  conducting objects not otherwise connected adequately.  Grounding is the electrical connecting of a conducting  object to the primary structure for return of current. Primary  structure is the main frame, fuselage, or wing structure of  the aircraft. Bonding and grounding connections are made  in aircraft electrical systems to: Aluminum terminal lugs should be placed over a plated  brass plain washer, followed with another plated brass plain  washer, split steel lockwasher, and plain nut or elastic stop  nut. The plated brass washer should have a diameter equal to  the tongue width of the aluminum terminal lug. Consult the  manufacturer’s instructions for recommended dimensions of  these plated brass washers. Do not place any washer in the  current path between two aluminum terminal lugs or between  two copper terminal lugs. Also, do not place a lockwasher  directly against the tongue or pad of the aluminum terminal. To join a copper terminal lug to an aluminum terminal lug,  place a plated brass plain washer over the nut that holds the  stud in place; follow with the aluminum terminal lug, a plated  brass plain washer, the copper terminal lug, plain washer, split  steel lockwasher and plain nut or self-locking, all metal nut.  As a general rule, use a torque wrench to tighten nuts to ensure  sufficient contact pressure. Manufacturer’s instructions  provide installation torques for all types of terminals.  Figure 4-109.  Connecting terminals to terminal block. Figure 4-108.  Repairing broken wire by soldering and potting. 2.  Strip approximately 1½ inches from each broken end  of the wire. 3.  Lay the stripped ends side by side and twist one wire  around the other with approximately four turns. 4.  Twist the free end of the second wire around the first  wire with approximately four turns. Solder the wire  turns together using 60 ⁄ 40  tin-lead resin-core solder. 5.  When solder is cool, draw the sleeve over the soldered  wires and tie at one end. If potting compound is  available, fill the sleeve with potting material and  tie securely. 6.  Allow the potting compound to set without touching  for 4 hours. Full cure and electrical characteristics are  achieved in 24 hours. Bonding and Grounding Connecting Terminal Lugs to Terminal  Blocks 1.  Protect aircraft and personnel against hazards from  lightning discharge, 2.  Provide current return paths, 3.  Prevent development of radio-frequency potentials, 4.  Protect personnel from shock hazard, 5. Provide stability of radio transmission and  reception, and