TM 1-1510-225-10 2-48 b.  Operation.        The    fire    extinguisher    control switch-indicators,   which   are   used   to   discharge   the extinguisher  system,  are  located  on  the  glareshield  at each   end   of   the   warning   annunciator   panel.      Each push   to   activate   switch-indicator   consists   of   three annunciators.        A    red    annunciator    placarded    D, indicates   that   the   system   has   been   discharged,   a green   annunciator,   placarded    OK,   is   provided   for system test.  To discharge the extinguisher, raise the safety  wired  clear  plastic  cover  and  press  the   ENG FIRE  PUSH  TO  EXT switch-indicator.  These controls receive   power   from   the   hot   battery   bus.      The   fire extinguisher     will     be     completely     expended     upon activation.    The  yellow   D  annunciator  will  illuminate and  remain  illuminated,  regardless  of  battery  switch position    until    the    pyrotechnic    cartridge    has    been replaced. c.   Fire  Extinguisher  TEST  SWITCH.    The  fire extinguisher   system   test   switch   is   used   to   test   the circuit integrity of the fire extinguishing system.  During preflight, the pilot should rotate the  TEST SWITCH to the   EXT    R    and    EXT   L    positions    and    verify    the illumination of the yellow  D annunciator and the green OK   annunciator  on  each  fire  extinguisher  activation switch on the glareshield. d.  Fire    Extinguisher    Pressure    Gauge.        A gauge,   calibrated   in   psi,   is   provided   on   each   fire extinguisher  supply  cylinder  for  determining  the  level of   charge.      The   gauges   should   be   checked  during preflight.  Refer to Table 2-1 for appropriate pressure. 2-26.  OIL SUPPLY SYSTEM. CAUTION Maximum    allowable    oil    consumption    is 1 quart in 5 hours of engine operation. a.   Engine   Oil   Tank.    The  engine  oil  tank  is integral with the air-inlet casting located forward of the accessory  gearbox.    An  external  line  from  the  high- pressure pump supplies oil for propeller operation and lubrication    of    the    reduction    gearbox    and    engine bearings.    Two  scavenge  lines  return  oil  to  the  tank from     the     propeller     reduction     gearbox.        A    non- congealing,  external  oil  cooler  keeps  the  engine  oil temperature  within  operating  limits.    The  capacity  of each  engine  oil  tank  is  2.5  U.S.  gallons.    The  total system capacity for each engine, which includes the oil tank,  oil  cooler,  lines,  etc.,  is  approximately  3.5  U.S. gallons.      A   dipstick   attached   to   the   oil   filler   cap indicates  the  oil  level.    Oil  grade,  specifications,  and servicing points are described in Section XII, Servicing, Parking, and Mooring. b.  Engine Oil System.    The  oil  system  of  each engine is coupled to an oil cooler unit (radiator) of fin- and-tube  design.    The  oil  cooler  unit,  located  in  the lower  aft  nacelle  below  the  engine  air  intake,  is  the only airframe-mounted pan of the oil system.  Each oil cooler incorporates a thermal bypass valve that assists in  maintaining  oil  at  the  proper  temperature  range  for engine operation. 2-27.  ENGINE IGNITION SYSTEM. a.   Description.     The  basic  ignition  system  for each  engine  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   IGNITION  switches.   Placing   either   ENGINE   START   switch   to   the   ON position will cause the respective engine to motor and 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.  Ignition  and  Engine  Start  Switches.     Two three-position   toggle   switches,   placarded   IGNITION AND   ENGINE   START   LEFT   /   RIGHT   ON   /   OFF STARTER ONLY, are located on the pilot's subpanel.   These    switches    will    initiate    starter    motoring    and ignition in the  ON position, or will motor the engine in the STARTER ONLY position.  The ON switch position completes    the    starter    circuit    for    engine    rotation, energizes  the  igniter  plugs  for  fuel  combustion,  and activates    the    respective    L    IGNITION    ON    or    R IGNITION   ON   annunciator   on   the   caution/advisory annunciator panel.  The center switch position is OFF.   Two   5-ampere   circuit   breakers   on   the   left   sidewall circuit   breaker   panel,   Figure   2-16,   placarded   LEFT and   RIGHT   IGNITOR   POWER,   protect   the   ignition circuits.    Two  5-ampere  circuit  breakers  on  the  left sidewall   circuit   breaker   panel,   placarded   LEFT  and RIGHT  START  CONTROL,  protect  the  starter  control circuits. Table 2-1.  Engine Fire Extinguisher Gauge Pressure TEMP °C -40 -29 -18 -06 04 16 27 38 48 PSI 190 to 240 220 to 275 250 to 315 290 to 365 340 to 420 390 to 480 455 to 550 525 to 635 605 to 730