TM 55-1510-222-10 b. Engine Air Inlet Anti-Ice System. (1) Description.  A small duct, facing into the exhaust flow of the engine's left exhaust stack, 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  to  the engine's 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.    Each  fuel  control  unit  is  also  protected against ice.  Fuel control heat is automatically provided during 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,  fourteen fuel   nozzles   and   a   purge   system.      The   fuel   purge system  forces  residual  fuel  from  the  manifolds  to  the combustion chamber where it is consumed. b.    Fuel  Control  Unit.    One  fuel  control  unit  is mounted on the accessory case of the engine.  This unit is a hydro-pneumatic metering device which determines the proper fuel flow 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   gas generator (N₁) speed.  N₁ speed is controlled by engine gas  generator  (N₁)  speed.    N₁  speed  is  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  CUTOFF  position,  which  shuts  off the fuel supply. 2-22.  POWER LEVERS. CAUTION Moving  the  power  levers  below the  flight  idle  gate  without  the engines   running   may   result   in damage to the reverse mechanism linkage. The  two  power  levers  are  located  in  the  control pedestal (fig. 2-11), and are placarded POWER.  These levers  regulate  power  in  the  reverse,  idle  and  forward ranges,  operating  so  that  forward  movement  increases engine  power.    Power  control  is  accomplished  through adjustment of the N₁ speed governor in the fuel control unit.    Power  is  increased  when  N₁  RPM  is  increased. The  power  levers  also  control  propeller  reverse  pitch. Distinct movement (pulling up and then aft on the power lever) by the pilot is required for operation in the ground fine  and  reverse  ranges.    Upper  lever  travel  range  is designated INCR (increase), supplemented by an arrow pointing  forward.    Lever  travel  range  is  marked  IDLE, LIFT, GROUND FINE, LIFT and REVERSE.  A placard below   the   lever   slots   reads:   CAUTION   -   REVERSE ONLY WITH ENGINES RUNNING. 2-23.  CONDITION LEVERS. The two condition levers are located in the control pedestal (fig. 2-11).  Each lever starts and stops the fuel supply, and controls the idle speed for its engine.  The levers  have  three  placarded  positions:  FUEL  CUTOFF, LOW  IDLE,  and  HIGH  IDLE.    In  the  FUEL  CUTOFF position,  the  condition  lever  controls  the  cutoff  function of   its   engine-mounted   fuel   control   unit.      From   LOW IDLE  to  HIGH  IDLE,  they  control  the  governors  of  the fuel control units to establish minimum fuel flow levels. LO  IDLE  position  sets  the  fuel  flow-rate  to  attain  60  to 62% (at sea level) minimum N₁ and HIGH IDLE position sets  the  rate  to  attain  71  to  73%  minimum  N₁.    The power lever for the corresponding engine can select N₁ the  respective  idle  setting,  up  to  maximum  power.    An increase in low idle N₁ will  be  experienced  at  high  field elevation. 2-24.  FRICTION LOCK KNOBS. Four  friction  lock  knobs  (fig.  2-11)  are  located  in the control pedestal to adjust friction drag.  One knob is below   the   propeller   levers,   one   below   the   condition levers,   and   two   below   the   power   levers.      When   the knobs    are    rotated    clockwise,    friction    is    increased opposing movement of the affected lever as set by the pilot.        Counterclockwise    rotation    of    the    knobs    will decrease  friction,  thus  permitting  free  and  easy  lever movement.  Two FRICTION LOCK placards are located in the pedestal adjacent to the knobs. 2-25.  ENGINE FIRE DETECTION SYSTEM. a.        Description.        A    fire    detection    system    is installed to provide an immediate warning in the 2-23