are made up of the following components: canopy caution  light  on  the  cockpit  left  digital  display indicator,  master  caution  light  on  the  left-hand advisory and threat warning indicator panel, and the  maintenance  code  display  on  the  nosewheel well  digital  display  indicator. NORMAL   OPERATION Learning  Objective:   Identify  the  canopy normal  mode  of  operation  to  include  the manual  backup  mode. The  canopy  is  operated  electrically  by  the external  or  internal  canopy  control  switches  in  the normal  control  mode.  The  canopy  can  also  be operated manually in the backup manual control mode  if  electrical  power  is  not  available. NORMAL  CONTROL  MODE The  canopy  may  be  operated  with  the  external canopy  control  switch.  To  open  the  canopy,  the switch is held in the OPEN position. The canopy stops  automatically  when  the  full  open  position is reached. To close the canopy, the switch is held in  the  CLOSE  position  until  the  canopy  closes, moves full forward, and locks. The canopy stops automatically  when  the  closed  and  locked  position is reached. Motion may be stopped at any point during  opening  or  closing  by  releasing  the  switch. The  switch  returns  to  the  HOLD  position  when released. To open the canopy internally with weight on the wheels, the internal canopy control switch is set  to  OPEN  and  released.  The  switch  is magnetically held in the OPEN position until the canopy raises to full open and stops. The switch then  returns  to  HOLD.  Canopy  motion  may  be stopped  at  any  point  during  canopy  opening  by manually setting the switch to the HOLD position, which  overrides  the  magnetic  holding  coil.  The internal canopy control switch opening circuit is equipped with a weight-off-wheels relay that de- energizes  the  magnetic  holding  coil  when  the aircraft is in a weight-off-wheels condition. With the holding coil de-energized, the switch must be manually   held   to   the   OPEN   position   when opening  the  canopy. When the canopy closes, moves full forward, and locks, the No. 4 right canopy latch depresses t h e    c a n o p y    p o s i t i on switch   plunger. Simultaneously, the canopy actuator arm rotates overcenter  and  depresses  the  canopy  locked  switch plunger. Depressing both switch plungers causes the master caution light and the canopy display on the left digital display indicator to extinguish, indicating the canopy is fully closed and locked. If both switches are not fully depressed or a failure occurs  in  either  switch,  the  master  caution  and canopy  caution  indicators  will  remain  illuminated. If both switch plungers are not depressed within 15 seconds, the canopy switches disagree and the maintenance code (889) will be displayed on the nosewheel  well  digital  display  indicator. Electrical   inputs   supplied   to   the   canopy actuator are transformed into mechanical motion used to raise and lower the canopy. The actuator is equipped with an up-travel-limit switch, which automatically  interrupts  power  to  the  actuator when the full open position is reached. With no aircraft   generator   power   or   external   power applied,   a   utility   battery   supplies   power   for at least five open and close cycles of the canopy. On   some   F/A-18   aircraft,   a   logic   circuit   in the   battery   and   charger   unit   secures   the canopy  control  power  when  the  battery  voltage drops   below   19±1   volts. Due   to   decreased   battery   capacity   at   low temperatures,   canopy   operation   using   battery power  is  not  recommended  when  ambient  tem- perature  is  below  0°F.  Under  these  conditions, external  electrical  power  should  be  used.  When external  power  is  not  available,  the  canopy  can be  operated  using  the  backup  manual  control mode. To further understand how the opening and closing  cycles  function,  refer  to  figure  2-9. BACKUP  MANUAL  CONTROL  MODE The  backup  manual  control  mode  is  used  to open  and  close  the  canopy  when  utility  battery power  is  low,  internal  or  external  electrical  power is not available, or a failure has occurred in the canopy  actuation  control  system. The  canopy  actuator  manual  drive  unit  is operated  from  inside  the  cockpit  by  using  the internal   manual   canopy   opening   handle.   The handle  is  removed  from  its  stowage  receptacle  and clip, and then it is inserted into the crank socket. The  handle  is  turned  70±1  turns  clockwise  to close the canopy or counterclockwise to open the canopy.   The   internal   manual   canopy   opening handle shaft assembly mechanically links the drive unit to the canopy actuator. By operating the drive unit internally or externally, mechanical motion is transferred through the shaft assembly to the canopy   actuator. 2-7