1. A pigtail of one-fourth to one-half inch (three to six twists) should be made at the end of the wiring. This  pigtail  must  be  bent  back  or  under  to  prevent  it from becoming a snag. 2. The    safety    wire    must    be    new    upon    each application. 3. When  you  secure  castellated  nuts  with  safety wire,  tighten  the  nut  to  the  low  side  of  the  selected torque range, unless otherwise specified. If necessary, continue tightening until a slot aligns with the hole. 4. All safety wires must be tight after installation, but  not  under  such  tension  that  normal  handling  or vibration will break the wire. 5. Apply the wire so that all pull exerted by the wire tends to tighten the nut. 6. Twists should be tight and even, and the wire between the nuts should be as taut as possible without being overtwisted. COTTER PINS Use  cotter  pins  to  secure  bolts,  screws,  nuts,  and pins.  Some  cotter  pins  are  made  of  low-carbon  steel, while others consist of stainless steel, and thus are more resistant to corrosion. Use stainless steel cotter pins in locations   where   nonmagnetic   material   is   required. Regardless of shape or material, use all cotter pins for the   same   general   purpose—safetying.   Figure   5-27 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 shorter prong. Cotter pin installation is shown in figure 5-28. Use castellated  nuts  with  bolts  that  have  been  drilled  for cotter  pins.  Use  stainless  steel  cotter  pins.  The  cotter pin   should   fit   neatly   into   the   hole,   with   very   little sideplay. The following general rules apply to cotter pin safetying: !    Do not bend the prong over the bolt end beyond the bolt diameter. (Cut it off if necessary.) !    Do not bend the prong down against the surface of the washer. (Again, cut it off if necessary.) !    Do  not  extend  the  prongs  outward  from  the sides    of    the    nut    if    you    use    the    optional wraparound method. !    Bend   all   prongs   over   a   reasonable   radius. Sharp  angled  bends  invite  breakage.  Tap  the prongs lightly with a mallet to bend them. Q5-11. What   is   the   purpose   of   safetying   aircraft hardware? Q5-12. What  is  the  most  common  method  of  safety wiring? Q5-13. What    are    the    two    methods    of    safetying turnbuckles used by the military services? Q5-14. What type of cotter pin should you use when nonmagnetic material is required? WASHERS LEARNING  OBJECTIVE: Recognize  the two  primary  functions  of  washers  as  used  in aircraft/engine construction. Washers used in aircraft structures may be grouped into  three  general  classes—plain,  lock  washers,  and 5-19 ANF0527 UNEVEN PONG OPTIONAL DIAMETER LENGTH Figure 5-27.—Types of cotter pins. ANF0528 PREFERRED OPTIONAL Figure 5-28.—Cotter pin installations.