2-20. ENGINE ICE PROTECTION SYSTEMS. a.   Inertial   Separator. After   the   ice   vanes   have   been   manually extended,  they  may  be  mechanically  actu- ated  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  opera- tion  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  condi- tions.  A  movable  vane  and  a  bypass  door  are  low- ered  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  pro- vided,  and  is  actuated  by  pulling  the  T-handles  just below  the  pilot’s  subpanel  placarded  ICE  VANE  - No.  1  ENG  -  No.  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  parti- cles   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,  No.  1  VANE EXT and No. 2 VANE EXT. (3.)  In  the  non-ice  protection  mode,  the vane  and  bypass  door  are  retracted  out  of  the  air- stream  by  placing  the  ice  vane  switches  in  the RETRACT  position.  The  green  annunciator  lights will  extinguish.  To  assure  adequate  oil  cooling, retraction  should  be  accomplished  at  15°C  and above.  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  15  seconds,  a  yel- low  No.  1  VANE  FAIL  or  No.  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.   During   manual   system   use,   the   electric motor  switch  position  must  match  the  manual  han- dle  position  for  a  correct  annunciator  readout. TM  55-1510-221-10 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.)   Fuel   heater. An   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  fuel  control  unit  is  protected against  ice.  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  con- trol  unit,  a  fuel  flow  divider,  a  dual  fuel  manifold and  fourteen  fuel  nozzles.  The  fuel  flow  divider  acts as  a  drain  valve  to  clear  residual  fuel  after  engine shutdown. b.  Fuel  Control  Unit.  One  fuel  control  unit  is mounted  on  the  accessory  case  of  each  engine.  This unit  is  a  hydro-pneumatic  metering  device  which determines  the  proper  fuel  schedule  for  the  engine  to produce  the  amount  of  power  requested  by  the  rela- tive  position  of  its  power  lever.  The  control  of  devel- oped  engine  power  is  accomplished  by  adjusting  the engine   compressor   turbine   (N₁)  speed.  N₁ speed  is controlled  by  varying  the  amount  of  fuel  injected into  the  combustion  chamber  through  the  fuel  noz- zles.   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. Moving  the  power  levers  into  reverse range   without   the   engines   running   may result  in  damage  to  the  reverse  linkage mechanism. Two   power   levers   are   located   on   the   control pedestal (fig. 2-7). These levers regulate power in the reverse,  idle,  and  forward  range,  and  operate  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 2-23