TM 1-1510-225-10 2-31 Section II.  EMERGENCY EQUIPMENT 2-12.  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. 2-13.  HAND-OPERATED FIRE EXTINGUISHER. Avoid  repeated  or  prolonged  exposure  to high concentrations of monobromo- trifluoromethane (CF₃Br) or decomposition products.    The  liquid  shall  not  be  allowed to  come  into  contact  with  the  skin,  as  it may   cause   frostbite   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  is located in the left cabin sidewall, aft of the cabin door.   They  are  of  the  monobromotrifluoromethane  (CF₃Br) type.    Each  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 2-14.  ENGINES. Two  PT6A-42  turboprop  engines,  rated  at  850 SHP  each,  power  the  aircraft.    Refer  to  Figure  2-10.   Each engine is equipped with a hydraulically controlled, reversible, constant-speed, four-blade, full- feathering   propeller.      The   engines   are   reverse-flow free  turbines,  and  each  employs  a  three-stage  axial compressor and a single-stage centrifugal compressor in  combination,  driven  by  the  gas  generator  turbine.   The gas generator turbine and the two power turbines are  in  line  and  have  opposite  rotations.    The  power turbines   are   connected   through   planetary   reduction gearing to a flanged propeller shaft.  The oil tank, filler cap and dipstick are an integral part of the engine. NOTE The    engine   anti-ice   system   (ice   vanes) should   be   on   (extended)   for   all   ground operations to minimize ingestion of ground debris.  Turn off engine anti-ice (retract ice vanes)   to   maintain   engine   temperatures within limits.  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 the air 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  turbines,  then  is  routed  through  two  exhaust ports  near  the  front  of  the  engine.    A  pneumatic  fuel control  system  schedules  fuel  flow  to  maintain  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,  oil  pump, refrigerant compressor (right engine), starter/ generator,    and    the    tachometer    generator.        The reduction    gearbox    forward    of    the    power    turbine provides    gearing    for    the    propeller    and    drives    the propeller tachometer generator, the propeller overspeed governor, and the propeller primary governor. 2-15.  ENGINE COMPARTMENT COOLING. The  forward  engine  compartment,  including  the accessory section, is cooled by air that enters around the    exhaust    stack    cutouts    and    through    the    gap between  the  propeller  spinner  and  forward  cowling, and exhausts through louvers in the upper forward and aft cowling. WARNING