TM 55-1510-219-10 2-19.  FOREIGN OBJECT DAMAGE CONTROL. The    engine    has    an    integral    air    inlet    screen designed to obstruct objects large enough to damage the compressor. 2-20.  ENGINE ICE PROTECTION SYSTEMS. a. Inertial Separator. CAUTION After    the    ice    vanes    have    been manually   extended,   they   may   be mechanically   actuated   only.      No electrical    extension    or    retraction shall   be   attempted   as   damage   to the actuator may result.  Linkage in the nacelle area must be reset prior to operation of the electric 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  5'C  or colder,     by     energizing     electrical     actuators     with     the switches,    placarded    ICE    VANE    RETRACT    EXTEND, located  on  the  overhead  control  panel.    A  mechanical backup system is provided, and is actuated by pulling the T-handles  just  below  the  pilot's  subpanel  placarded  ICE VANE #1 ENG #2 ENG.  Decrease airspeed to 160 knots or  less  to  reduce  forces  for  manual  extension.    Normal airspeed may then be resumed. (1) The vane deflects the ram airstream slightly downward  to  introduce  a  sudden  turn  in  the  airstream  to the engine, causing the moisture particles to continue on undeflected,  because  of  their  greater  momentum,  and  to be discharged overboard. (2) While in the icing flight mode, the extended position of the vane and bypass door is indicated by green annunciator lights, #1 VANE EXT and #2 VANE EXT. (3) In  the  non-ice  protection  mode,  the  vane and  bypass  door  are  retracted  out  of  the  airstream  by placing  the  ice  vane  switches  in  the  RETRACT  position. The  green  annunciator  lights  will  extinguish.    Retraction should  be  accomplished  at  15°C  and  above  to  assure adequate    oil    cooling.        The    vanes    should    be    either extended or retracted; there are no intermediate positions. (4) If  for  any  reason  the  vane  does  not  attain the  selected  position  within  approximately  15  seconds,  a yellow  #1  VANE  FAIL  or  #2  VANE  FAIL  light  illuminates on the caution/advisory panel.  In this event, the manual backup   system   should   be   used.      When   the   vane   is successfully    positioned    with    the    manual    system,    the yellow annunciator lights will extinguish. b. Engine Air Inlet Deice System. (1) Description.      Hot   engine   exhaust   gas   is utilized   for   heating   the   air   inlet   lips   to   prevent   the formation  of  ice.    Hot  exhaust  gas  is  picked  up  inside each engine exhaust stack and carried by plumbing to the inlet lip.  The gas flows through the inside of the lip to the bottom where it is allowed to escape. (2) Engine    air    inlet    deice    system    switches. (Provisions  only  system  not  installed.    )  Two  switches placarded   ENG   INLET   LIP   HEAT   #1,   #2   OFF/   ON, located  on  the  overhead  control  panel,  operate  solenoid valves  in  the  exhaust  system  of  each  engine.    These valves control the flow of hot exhaust gases to the inlet air lip assemblies. (3) Fuel  heater.    A  oil-to-fuel  heat  exchanger, located on the engine accessory case, operates continuously and automatically to heat the fuel sufficiently to   prevent   ice   from   collecting   in   the   fuel   control   unit. Each pneumatic fuel control line is protected against ice. Power   is   supplied   to   each   fuel   control   air   line   jacket heater by two switches actuated by moving the condition levers  in  the  pedestal  out  of  the  fuel  cutoff  range.    Fuel control   heat   is   automatically   turned   on   for   all   engine operations. 2-21.  ENGINE FUEL CONTROL SYSTEM. a. Description.        The    basic    engine    fuel    system consists of an engine driven fuel pump, a fuel control unit, a fuel flow divider, a dual fuel manifold and fourteen fuel nozzles. b. Fuel    Control    Unit.        One    fuel    control    unit    is mounted on the accessory case of each engine.  This unit is a hydro-mechanical metering device which determines the  proper  fuel  schedule  for  the  engine  to  produce  the amount of power requested by the relative position of its power  lever.    The  control  of  developed  engine  power  is accomplished by adjusting the engine compressor turbine (N1) speed.  N speed controlled by varying the amount of fuel  injected  into  the  combustion  chamber  through  the fuel    nozzles.        Engine    shutdown    is    accomplished    by moving   the   appropriate   condition   lever   to   the   full   aft, FUEL CUT-OFF position, which shuts off the fuel supply. 2-24