TM 55-1510-219-10 Section II: EMERGENCY EQUIPMENT 2-13.  DESCRIPTION. The equipment covered in this section includes all emergency equipment, except that which forms part of a complete  system.    For  example,  landing  gear  system, etc.    Chapter  9  describes  the  operation  of  emergency exits and location of all emergency equipment. 2-14.  FIRST AID KITS. Four first aid kits are included in the survival kit. 2-15.  HAND-OPERATED FIRE EXTINGUISHER. WARNING Repeated   or   prolonged   exposure   to high concentrations of monobromotrifluo- romethane   (CF₃Br)   or   decomposition products   should   be   avoided.      The liquid   shall   not   be   allowed   to   come into  contact  with  the  skin,  as  it  may cause   frost   bite   or   low   temperature burns  because  of  its  very  low  boiling point. One  hand-operated  fire  extinguisher  is  mounted below the pilot's seat and a second extinguisher, located on  the  left  cabin  sidewall,  aft  of  the  cabin  door.    They are   of   the   monobromotrifluoromethane   (CF₃Br)   type. The extinguisher is charged to a pressure of 150 to 170 PSI  and  emits  a  forceful  stream.    Use  an  extinguisher with  care  within  the  limited  area  of  the  cabin  to  avoid severe splashing. NOTE Engine  fire  extinguisher  systems  are described in Section III. Section III.  ENGINES AND RELATED SYSTEMS 2-16.  DESCRIPTION. The aircraft is powered by two PT6A-41 turboprop engines (fig.  2-10).  The engine has a three stage axial, single  stage  centrifugal  compressor,  driven  by  a  single stage reaction turbine.  The power turbine, a two stage reaction   turbine,   counter-rotating   with   the   compressor turbine,  drives  the  output  shaft.    Both  the  compressor turbine    and    the    power    turbine    are    located    in    the approximate   center   of   the   engine   with   their   shafts extending  in  opposite  directions.    Being  a  reverse  flow engine, the ram air supply enters the lower portion of the nacelle   and   is   drawn   in   through   the   aft   protective screens.    The  air  is  then  routed  into  the  compressor. After   it   is   compressed,   it   is   forced   into   the   annular combustion    chamber,    and    mixed    with    fuel    that    is sprayed in through 14 nozzles mounted around the gas generator  case.    A  capacitance  discharge  ignition  unit and two spark igniter plugs are used to start combustion. After    combustion,    the    exhaust    passes    through    the compressor turbine and two stages of power turbine and is routed through two exhaust ports near the front of the engine.  A pneumatic fuel control system schedules fuel flow  to  maintain  the  power  set  by  the  gas  generator power lever.  The accessory drive at the aft end of the engine provides power to drive the fuel pumps, fuel  control,  the  oil  pumps,  the  refrigerant  compressor (right   engine),   the   starter/generator,   and   the   turbine tachometer transmitter.  The reduction gearbox forward of  the  power  turbine  provides  gearing  for  the  propeller and   drives   the   propeller   tachometer   transmitter,   the propeller overspeed governor, and the propeller governor.    A  torque  limiter  is  incorporated  on  the  front case   of   the   propeller   reduction   gearbox   to   maintain developed engine torque within design limits. 2-17.  ENGINE COMPARTMENT COOLING. The   forward   engine   compartment   including   the accessory  section  is  cooled  by  air  entering  around  the exhaust  stack  cutouts,  the  gap  between  the  propeller spinner   and   forward   cowling,   and   exhausting   through ducts in the upper and lower aft cowling. 2-18.  AIR INDUCTION SYSTEMS GENERAL. Each   engine   and   oil   cooler   receives   ram   air ducted   from   an   air   scoop   located   within   the   lower section  of  the  forward  nacelle.    Special  components  of the   engine   induction   system   protect   the   power   plant from icing and foreign object damage. 2-22