TM 1-1510-225-10 2-34 2-16.  AIR INDUCTION SYSTEMS – GENERAL. Each   engine   and   oil   cooler   receives   ram   air ducted from separate air inlets located within the lower section   of   the   forward   nacelle.      Induction   system components  protect  the  power  plant  from  icing  and reduce the possibility of foreign object damage. 2-17.  FOREIGN OBJECT DAMAGE CONTROL. The    engine    has    an    integral    air    inlet    screen designed  to  obstruct  objects  large  enough  to  damage the compressor. 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.  2-18.  ENGINE ICE PROTECTION SYSTEMS  R . a.   Inertial   Separator.      An   inertial   separation system  is  built  into  each  engine  air  inlet  to  prevent moisture    particles    from    entering    the    engine    inlet plenum under icing conditions.  A movable vane and a bypass   door   are   lowered   into   the   air   stream   when operating   in   visible   moisture   at   5   °C   or   colder,  by energizing    electrical    actuators    with    the    switches, placarded  LEFT and  RIGHT  ENGINE  ANTI-ICE  ON / OFF,   located   on   the   pilot's   subpanel.      The   system incorporates an electrical backup system that operates identically to the main system.  The back-up ice  vane system is controlled by two switches placarded  LEFT and  RIGHT  ACTUATOR  MAIN /  STANDBY, located on   the   pilot's   subpanel.      If   the   main   system   fails, placing the switch in the  STANDBY position will allow use  of  the  back-up  system.    Electrical  protection   is provided     through     two     5-ampere     circuit     breakers placarded  LEFT and   RIGHT  MN  ENG  ANTI-ICE  and two  5-ampere  circuit  breakers,  placarded    LEFT  and RIGHT   STBY   ENG   ANTI-ICE,   located   on   the   right sidewall circuit breaker panel. b.  Engine Ice Protection Systems Operation.   The vane deflects the ram airflow slightly downward to introduce  a  sudden  turn  in  the  airflow  to  the  engine.   Because    of    their    greater    momentum    the    particles continue undeflected and are discharged overboard. Once    the    ice    vane    system    is    actuated,    the extended   position   of   the   vane   and   bypass   door   is indicated  by  green  annunciators,  placarded L  and R ENG ANTI-ICE, located on the caution/advisory panel.   If for any reason the vane(s) do not attain the selected position  within  33  seconds,  a  yellow L  or  R  ENG  ICE FAIL    annunciator    will    illuminate    on    the    caution/ advisory panel.  In this event, the appropriate LEFT or RIGHT   ACTUATOR  switch  should  be  placed  in  the STANDBY  position.    Once  the  vane  is  successfully positioned,    using    the    standby    system,    the    yellow annunciator(s) will extinguish and the applicable green LEFT   or   RIGHT   ENG   ANTI-ICE   annunciator(s)  will illuminate. c.   Engine Anti -Ice System. (1)   Air  Inlet.    A  small  duct,  which  faces  into the   exhaust   flow   in   the   left   exhaust   stack   of   each engine,  diverts  a  small  portion  of  the  engine  exhaust gases   to   the   engine   air   inlet   lip.      The   gases   are circulated   through   the   engine   air   inlet   lip   and   then exhausted  through  a  duct  in  the  right  exhaust  stack.   The   continuous   flow   of   hot   engine   exhaust   gases heats  the  engine air inlet lip, preventing the formation of ice. (2)   Fuel Heater. An oil-to-fuel heat exchanger,   located   in   the   engine   accessory   case, operates  continuously  and  automatically  to  heat  the fuel sufficiently to prevent ice from collecting in the fuel control unit. (3)   Fuel   Control   Heat.        The    engine    fuel control  unit  is  protected  from  icing  by  the  fuel  control heater,     which     is     actuated     by     movement     of     its respective   condition   lever.      The   fuel   control   heater circuit   breaker,   placarded   LEFT  and    RIGHT   FUEL  CONTROL   HEAT,   is   located   on   the   right   sidewall circuit breaker panel. 2-19.  ENGINE ICE PROTECTION SYSTEMS T3 F3 .. a.   Ice Vanes (Inertial Separator System).    An inertial  separation  system  is  built  into  each  engine  air inlet  to  prevent  moisture  particles  from  entering  the engine inlet plenum under icing conditions.  A movable vane and a bypass door are lowered into the airstream when  operating  in  visible  moisture  at  an  OAT  or  SAT of +5°C or colder (IOAT or TAT of +10°C or colder for in   flight)   with   the   switches,   placarded   ICE   VANE EXTEND   /   RETRACT,    located    on    the    lower    left subpanel. The   vane   deflects   the   ram   airstream   slightly downward to induce a sudden turn in the airstream to the  engine  causing  the  moisture  particles  to  continue undeflected, because of their greater momentum, and to be discharged overboard. While   in   the   icing   flight   mode,   the   extended position  of  the  vane  and  bypass  door  is  indicated  by green annunciator lights, L ICE VANE EXT and  R ICE VANE EXT.