TM 1-1500-204-23-1 f. Control     System     Components.          Control system    components    are    explained    in    the    following paragraphs. (1) Turnbuckles.    A  turnbuckle  assembly is a mechanical screw device consisting of two threaded terminals  and  a  threaded  barrel.    Figure  9-25  shows  a typical  turnbuckle  assembly.    Turnbuckles  are  fitted  in the  cable  assembly  for  the  purpose  of  making  minor adjustments   in   cable   length   and   for   adjusting   cable tension.    One  of  the  terminals  has  right-hand  threads and  the  other  has  left-hand  threads.    The  barrel  has matching right- and left-hand internal threads.  The end of  the  barrel  with  the  left-hand  threads  can  usually  be identified  by  a  groove  or  knurl  around  that  end  of  the barrel. (a) Turnbuckle replacement criteria. Replace   turnbuckles   and   turnbuckle   barrels   that   are cracked, corroded, or have stripped threads. (b) Turnbuckle tolerances. Turbuckle    tolerances    are    three    visible    male    (cable terminal)   threads   or   four   visible   female   (turnbuckle barrel)    threads,    each    of    which    should    be    free    of evidence  of  corrosion  at  the  root  of  the  threads.    (The maximum   of   four   visible   female   (turnbuckle   barrel) threads applies only to initial installation of the cable, so that    if    the    cable    stretches,    the    turnbuckle    can    be adjusted  to  the  desired  cable  tension,  at  which  time, more or less than four barrel threads may be exposed.) Safety all turnbuckles. (2) Cable terminals.  Terminal fittings are generally of the swaged type.  They are available in the threaded end, fork end, eye end, single-shank ball end, and double-shank ball end.  The threaded end, fork end, and eye end terminals are used to connect the cable to a  turnbuckle,  bellcrank,  or  other  linkage  in  the  system. The  ball-end  terminals  are  used  for  attaching  cables  to quadrants    and    special    connections    where    space    is limited.  Figure 9-26 shows the various types of terminal fittings.  Visually inspect and replace clevis or terminals that   are   scratched,   nicked,   dented,   corroded,   have stripped threads, or are found bent (distorted). NOTE Minor    nicks,    scratches,    corrosion pits,  less  than  0.005  inch  deep,  may be removed by cleaning and burnishing   smooth,   to   restore   the part to useful service. (3) Fairleads.      Fairleads,   as   shown   in figure  9-27,  are  used  to  guide  cables  in  a  straight  line through  or  between  structural  members  of  the  aircraft. Inspect fairleads for wear, breakage, alignment, cleanness,   and   security.      Examine   cable   routing   at fairleads to assure that deflection angles are no greater than  3  degrees  maximum.    Determine  that  all  guides and    anti-abrasion    strips    are    secure    and    in    good condition.  Replace rubber or nylon grommets that show evidence  of  excessive  wear.    Replace  worn  or  cracked phenolic    fairleads.        Reposition   fairleads    that    allow cables to chafe. (4) Pulleys.      Pulleys   are   used   to   guide cables  and  change  the  direction  of  cable  movement. Various cable system malfunctions may be detected by analyzing pulley conditions These include such discrepancies as too much tension, misalignment, pulley bearing problems, and size mismatches between cables and pulleys.  Examples of these conditions are shown in figure 9-28 inspect pulleys using the following procedures: (a) Reposition   pulleys   that   do   not align with cables within 2 degrees.  Replace inoperative or other- wise defective pulleys. (b) Inspect   pulleys   for   roughness, sharp edges, and presence of foreign     matenal embedded in the grooves. (c) Inspect    pulleys    for    excessive grooving  by  visual  examination  of  the  surface,  and  by rotating pulley and observing if the cable twists, rotates, or jumps up and down, as a result of interplay between the grooves of the pulley and the lay of the cable. (d) Examine pulley bearings to assure proper lubrication, smooth rotation, freedom from flat spots, dirt, and paint spray.  Inspect pulley bearings for  roughness,  binding,  noise,  rust,  lubricant  leakage, and excessive looseness compared to a new bearing. (e) Maintain    pulley    alignment    to prevent the cable from riding on the flanges and chafing against guards, covers, or adjacent structure. (f) Check   all   pulley   brackets   and guards for damage, alignment, and security.  Replace if cracked, corroded, or otherwise damaged. (g) Periodically rotate pulleys, which turn through a small arc, to provide a new bearing surface for the cable. 9-24