TM 1-1510-225-10 2-43 2-22.  CONDITION LEVERS. The  two  CONDITION  levers  are  located  on  the control pedestal.  Each lever starts and stops the fuel supply,  and  controls  the   idle  speed  for  its  respective engine.    The  levers  have  three  placarded  positions:   FUEL  CUTOFF,  LOW IDLE, and  HIGH  IDLE.    In  the FUEL    CUTOFF    position,     the    CONDITION    lever controls  the  cutoff  function  of  its  engine-mounted fuel control  unit.    From   LOW  IDLE  to  HIGH  IDLE,  they control   the   governors   of   the   fuel   control   units   to establish    minimum    fuel    flow    levels.        LOW   IDLE position  sets  the  fuel  flow  rate  to  attain  approximately 61% N₁ and HIGH IDLE position sets the rate to attain approximately  70%  N₁.      The   POWER  lever  for  the corresponding engine can select     N₁ from the respective  idle  setting,  up  to  maximum  power.    An increase in low idle N₁  will be experienced at high field elevation. 2-23.  FRICTION LOCK KNOBS. Friction drag of the engine and propeller control leve rs  is  adjusted,  as  applicable,  by  four  friction  lock knobs.  The friction lock knobs, placarded  FRICTION LOCK, are located on the control pedestal.  One knob is    below    the    propeller    levers,    one    is    below    the CONDITION  levers,  and  two  are  below  the   POWER leve rs.  When a knob is rotated clockwise, the friction increases opposing movement of the affected lever as set by the pilot.  Counterclockwise rotation of the knob will  decrease  friction,  thus  permitting  free  and  easy lever movement. 2-24.  ENGINE FIRE DETECTION SYSTEM. a.   Description    R  .    A  fire  detection  system  is installed to provide an immediate warning in the event of a fire or overtemperature in each engine compartment.      Refer   to   Figure  2 -12.      The   system consists   of   a   temperature   sensing   cable   for   each engine, two red warning annunciators, a test switch on the   copilot's   left   subpanel,   and   a   5-ampere   circuit breaker,   placarded   FIRE  DET   on  the  right  sidewall circuit breaker panel.  The test switch, placarded TEST SWITCH  ENG FIRE SYS EXT R / L and DET R / L, is located   on   the   copilot's   subpanel.      When   the   test switch   is   placed   in   the   DET   L   or   R   position,  the corresponding     L     ENG     FIRE or     R     ENG     FIRE annunciator on the warning annunciator panel and the MASTER  WARNING  annunciators  will  illuminate  and flash. NOTE The  system  may  be  tested  on  the  ground or in flight. When    a    fire    has    been    extinguished,    if    the integrity  of  the  system  has  not  been  destroyed,  the system will reset itself. b.  Description  T3   F3  OSA .  A pneumatic fire detection  system,  Figure  2-13,  is  installed  to  provide an  immediate  warning  in  the  event  of  a  fire  or  over- temperature  in  the  engine  compartment.    The  main element of the system is a temperature sensing cable routed continuously throughout either engine compartment,  terminating  in  a  responder  unit.    The responder  unit  is  mounted  in  each  engine  accessory area on the upper left hand engine truss just forward of the  engine  firewall.    The  responder  unit  contains  two sets of contacts:  a set of integrity switch contacts for continuity  test  functions  of   the  fire  detection  circuitry, and  a  set  of  alarm  switch  contacts  which  completes the circuit to activate the fire warning system when the detector  cable  senses  an  over-temperature condition in critical areas around the engine. The sensor cable consists of  an outer tube filled with  an  inert  gas,  and  an  inner  hydride  core  that  is filled  with  an  active  gas.    The  gases  within  the  tube form a pressure barrier that keeps the contacts of the responder    integrity    switch    closed    for    fire    alarm continuity  test  functions.    As  the  temperature  around the sensing cable increases, the gases within the tube begin    to    expand.        When    the    pressure    from    the expanding gases reaches a preset point, the contacts of   the   responder   alarm   switch   close,   causing   the respective ENG    FIRE    annunciator     and     flashing MASTER WARNING lights to illuminate. The   fire   warning   system   consists   of   two   red lenses   placarded   L   ENG   FIRE   and   R   ENG   FIRE, located   in   the   warning   annunciator   panel,   two   red MASTER WARNING  lights  located  on  opposite  sides of   the   glareshield,   and   two   responder   units   with pneumatic sensors in the engine compartments. An  integrity  switch  that  monitors  the  system  is held   in   the   closed   position.      If   the   detector   should develop  a  leak,  the  loss  of  gas  pressure  would  allow the   integrity   switch   to   open   and   signal   a   lack   of detector  integrity.    The  system  then  will  not  operate during the system test function.