TM 55-1510-219-10 2-29.  ENGINE CHIP DETECTION SYSTEM. A magnetic chip detector is installed in the bottom of   each   engine   nose   gearbox   to   warn   the   pilot   of   oil contamination and possible engine failure.  The sensor is an     electrically     insulated     gap     immersed     in     the     oil, functioning  as  a  normally-open  switch.    If  a  large  metal chip or a mass of small particles bridge the detector gap, a circuit is completed, sending a signal to illuminate a red annunciator panel indicator light placarded #1 or #2 CHIP DETR and the MASTER WARNING lights.  Chip detector circuits  are  protected  by  two  5-ampere  circuit  breakers, placarded CHIP DETR #1 and #2 on the overhead circuit breaker panel (fig.  2-26). 2-30.  ENGINE IGNITION SYSTEM. a. The basic ignition system consists of a solid state ignition exciter unit, two igniter plugs, two shielded ignition cables,  pilot  controlled  IGNITION  AND  ENGINE  START switches  and  the  ENG  AUTO  IGN  switch.    Placing  an IGNITION  AND  ENGINE  START  switch  to  ON  (forward) will  cause  the  respective  igniter  plugs  to  spark,  igniting the fuel/air mixture sprayed into the combustion chamber by  the  fuel  nozzles.    The  ignition  system  is  activated  for ground and air starts, but is switched off after combustion light up. b. One three-position toggle switch for each engine, located on the overhead control panel, will initiate starter motoring and ignition in the ON/ ENG START position, or will motor the engine in the STARTER ONLY (aft) position (fig.  2-18).  The switches are placarded #1 ENG START or  #2  ENG  START  to  designate  the  appropriate  engine. The  ON  switch  position  completes  the  starter  circuit  for engine    rotation,    energizes    the    igniter    plugs    for    fuel combustion,   and   activates   the   IGN   ON   light   on   the annunciator panel.  At center position the switch is OFF. Two   5-ampere   circuit   breakers   on   the   overhead   circuit breaker  panel,  placarded  IGNITOR  CONTR  #1  and  #2, protect ignition circuits.  Two 5ampere circuit breakers on the   overhead   circuit   breaker   panel,   placarded   START CONTR #1 and #2, protect starter control circuits (fig.  2- 26). 2-31.  AUTO IGNITION SYSTEM. If  armed,  the  auto  ignition  system  automatically provides  combustion  re-ignition  of  either  engine  should accidental flameout occur.  The system is not essential to normal    engine    operation,    but    is    used    to    reduce    the possibility  of  power  loss  due  to  icing  or  other  conditions. Each  engine  has  a  separate  auto  ignition  control  switch and a green indicator light placarded #1 or #2 IGN ON, on the  annunciator  panel.    Auto  ignition  is  accomplished  by energizing the two igniter plugs in each engine. NOTE The  system  should  be  turned  OFF during  extended  ground  operation to   prolong   the   life   of   the   igniter plugs. a. Auto  Ignition  Switches.    Two  switches  placarded ENG   AUTO   IGN   #1   or   #2,   control   the   auto   ignition systems.    The  ARM  position  initiates  a  readiness  mode for the auto ignition system of the corresponding engine. The  OFF  position  disarms  the  system.    Each  switch  is protected by a corresponding START CONTR #1 or #2 5- ampere  circuit  breaker  on  the  overhead  circuit  breaker panel (fig.  2-26). b. Auto  Ignition  Lights.      If   an   armed   auto   ignition system  changes  from  a  ready  condition  to  an  operating condition  (energizing  the  igniter  plugs  in  the  engine)  a corresponding green annunciator panel light will illuminate.  The annunciator panel light is placarded #1 or #2 IGN ON and indicates that the igniters are energized. The    auto    ignition    system    is    triggered    from    a    ready condition  to  an  operating  condition  when  engine  torque drops   below   approximately   20%.      Therefore,   when   an auto    ignition    system    is    armed,    the    igniters    will    be energized continuously during the time when an engine is operating   at   a   level   below   approximately   20%   torque. The    auto    ignition    lights    are    protected    by    5-ampere IGNITOR  CONTR  #1  or  #2  circuit  breakers,  located  on the overhead circuit breaker panel (fig.  2-26). 2-32.  ENGINE STARTER-GENERATORS. One  start-generator  is  mounted  on  each  engine accessory drive section.  Each is able to function either as a  starter  or  as  a  generator.    In  the  starter  function,  28 volts  DC  is  required  to  power  rotation.    In  the  generator function, each unit is capable of 400 amperes DC output. Each   starter   circuit   is   protected   by   a   5-ampere   circuit breaker    placarded    START    CONTR,    located    on    the overhead circuit breaker panel.  An automatic starter cut- off    is    installed    in    each    starter-generator    to    provide automatic  termination  of  the  start  cycle  at  approximately 40%  NI.    This  rotational  speed  is  sensed  by  a  magnetic sensor   internal   to   the   starter-generator.      For   additional information    on    the    starter-generator    system    refer    to Section IX. 2-33.  ENGINE INSTRUMENTS. The engine instruments  are vertically mounted near   the   center   of   the   instrument   panel   (fig.      2-28). 2-27