TM 1-1510-22310 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  complete  the  circuit  to  activate  the  fire warning   system   when   the   detector   (sensing   tubing) senses  an  overtemperature  condition  in  critical  areas around the engine.  The detector is dual functioning and responds  to  overall  "average"  temperature,  or  a  highly localized  "discrete"  temperature,  caused  by  flames  or hot gases.  Both the average and discrete temperatures are preset, and cannot be adjusted in the field. The sensor tubing consists of an outer tube filled with an inert  gas,  and  an  inner  gas  filled  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, activating the respective fire warning system. b. Warning   System.       The   fire   warning   system consists of two lenses, placarded # 1 FIRE PULL and # 2   FIRE   PULL   located   in   the   T   handles   below   the glareshield,    two    MASTER    WARNING    annunciators located  in  opposite  sides  of  the  glareshield,  and  two responder units with sensors in the engine compartments.    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. c. Testing.  Testing system integrity, availability of power, and the annunciators (#1 and #2 FIRE PULL and MASTER WARNING), is accomplished by two switches located   on   the   copilot's   subpanel.      The   switches   are placarded ENG FIRE TEST, DET OFF EXT, LEFT and RIGHT.  When either (LEFT or RIGHT) switch is placed in  the  DET  position,  electrical  current  flows  from  a  5- ampere circuit breaker placarded FIRE DEIR located on the  overhead  circuit  breaker  panel,  through  the  engine fire  detector  circuitry  to  the  integrity  switch  contacts  in the  respective  responder  unit,  causing  the  respective annunciators to illuminate.  If the circuit breaker opens, the system will not operate during a test, or activate the annunciators if the detector cable senses an overtemperature  condition.    The  system  may  be  tested either before, after, or in flight as desired. 2-26. ENGINE FIRE EXTINGUISHER SYSTEM. a. Description.         The     engine     fire     extinguisher system  (fig.    2-15),  consists  of  a  supply  cylinder,  an explosive squib, and valve located in each of the main gear wheel wells.  A gage calibrated in PSI is provided on   each   supply   cylinder   for   determining   the   level   of charge.  The extinguishing agent charge level should be checked during each preflight When fired, the explosive squlb  opens  the  valve,  releasing  all  of  the  pressurized extinguishing    agent    into    a    plumbing    network    The plumbing network terminates in spray nozzles, strategically  located  in  the  probable  fire  areas  of  the engine compartment b. Operation.   Fire  control  T  handles  used  to  arm the   extinguisher   system   are   centrally   located   on   the instrument panel, immediately below the glareshield (fig. 2-16).      These   controls   receive   power   from   the   hot battery  bus.    The  fire  detector  system  will  indicate  an engine   fire   by   illuminating   the   MASTER   WARNING annunciators on the glareshield and the respective #1 or #2 I;IRE PULL annunciators in the fire control T handles. Pulling the fire control T handle will electrically arm the extinguisher system and close the firewall shutoff valve for    that    particular    engine.        This    will    cause    the annunciator  in  the  PUSH  TO  EXTINGUISH  switch  and the  respective  #1  or  #2  FUEL  PRESS  annunciator  on the  warning  annunciator  panel  to  illuminate.  Pressing the  lens  of  the  PUSH  TO  EXTINGUISH  fire  switch  will fire  the  squib,  expelling  all  the  agent  in  the  cylinder  at one time.  A hinged plastic guard covers the PUSH TO EXTINGUISH     fire     switch     to     prevent     inadvertently actuating   the   fire   extinguish   switch   squib   circuit   The respective  caution  annunciator,  #  1  and  #  2  EXTGH DISCH  on  the  caution/advisory  annunciator  panel  and the  MASTER  CAUTION  annunciator  on  the  glareshield will illuminate and remain illuminated, regardless of the master switch position, until the squib is replaced. c. Testing.       The   test   switches   located   on   the copilot's  subpanel  (fig.    2-6),  are  placarded  ENG  FIRE TEST, DET OFFEXT, LEFT and RIGHT , and provide a test   of   the   fire   detection   and   extinguisher   circuitry. When   either   of   the   switches   is   placed   in   the   EXI' position,   the   corresponding   PUSH   TO   EXTINGUISH, SQUIB   OK,   and   EXTGH   DISCH   annunciators   should illuminate.    The  system  may  be  tested  either  before, after, or in flight as desired. A    gage    calibrated    in    PSI    is    mounted    on    each extinguishing  agent  supply  cylinder  for  determining  the level  of  charge  and  should  be  checked  during  preflight (table 2-1). 2-27. OIL SUPPLY SYSTEM. Maximum allowable oil consumption is one quart in 5 hours of engine operation. a.  The engine oil tank is integral with the air-inlet asting located forward of the accessory gearbox.  Oil for 2-28