TM 1-1510-223-10 of the three phase AC power busses. (5)   Three   phase   AC   external   power.     External three    phase    AC    power    for    operation    of    the    inertial navigation system or mission equipment can be applied to the aircraft through an external power receptacle located on  the  underside  of  the  left  wing  just  outboard  of  the engine   nacelle   (fig.      2-1).      The   receptacle   is   installed inside   the   wing   structure,   accessible   through   a   hinged access panel.  The AC electrical system is automatically isolated  from  the  external  power  source  if  the  external power is over or under voltage, over or under frequency, or has an improper phase sequence. (a)   Extenal  AC  power  annunciator.    The annunciator placarded EXT AC PWR ON, located on the mission    annunciator    panel    (fig.        4-1),    indicates    that external  AC  power  is  connected  to  the  3  phase  busses. The   EXTERNAL   POWER   annunciator   in   the   advisory annunciator   panel   indicates   that   an   AC   GPU   plug   is mated to the AC external power receptacle. (b)   External    AC    power    control    switch. The  switch  placarded  EXT  PWR  -  RESET  -  ON  -  OFF, located  on  the  mission  control  panel  (fig.    4-1),  controls application of three phase AC power to the aircraft Section X.  LIGHTING 2-75. EXTERIOR LIGHTING. Exterior  lighting  (fig.    2-32)  consists  of  a  navigation light   on   the   aft   end   of   the   aft   portion   of   the   vertical stabilizer, one standard navigation light on the outside of each wing tip pod; two strobe beacons, one on top of the horizontal stabilizer (directly above the vertical stabilizer) and  one  on  the  underside  of  the  fuselage  section;  dual landing  lights  and  a  taxi  light  mounted  on  the  nose  gear assembly;   a   recognition   light   located   in   the   outboard leading edge of each wing; two ice lights, one light flush mounted in each nacelle positioned to illuminate along the leading edge of each outboard wing; and emergency exit lights aft of the escape hatch and aft of the cabin door. a. Navigation   Lights.      The    navigation    lights    are protected by the 5-ampere circuit breaker placarded NAV on the overhead circuit breaker panel (fig.  2-7).  Control of  the  lights  is  provided  by  the  switch  placarded  NAV  - ON, located on the overhead control panel (fig.  2-13). b. Strobe  Beacons.     The  strobe  beacons  are  dual intensity   units.      They   are   protected   by   the   15-ampere circuit   breaker   placarded   BCN   on   the   overhead   circuit breaker panel (fig.  2-7).  Control of the lights is provided by    a    switch    located    on    the    overhead    control    panel placarded BEACON - DAY - NIGHT (fig.  2-13).  Placing the   switch   in   the   DAY   position   will   activate   the   high intensity   white   section   of   the   strobe   lights   for   greater visibility  during  daylight  operation  Placing  the  switch  in the   NIGHT   position   activates   the   lower   intensity   red portion of the strobe lights. c. Recognition   Lights.     The   recognition   lights   are operated  by  the  two-position  switch  placarded  RECOG, located in the pilot's subpanel.  The lights provide a very bright,  steady  illumination.    They  are  protected  by  a  7.5- ampere  circuit  breaker,  located  on  the  overhead  circuit breaker panel (fig.  2-7). d. Landing/Taxi  Lights.     Dual  landing  lights  and  a single taxi light are mounted on the nose gear assembly. The    lights    are    controlled    by    the    switches    placarded LANDING and TAXI, located on the pilot's subpanel.  The landing  light  circuit  is  protected  by  the  5-ampere  circuit breaker   placarded   LANDING,   located   on   the   overhead circuit  breaker  panel  (fig.    2-7).    The  taxi  light  circuit  is protected  by  a  5-ampere  circuit  breaker  placarded  TAXI, located  on  the  overhead  circuit  breaker  panel  (fig.    2-7). Landing/Taxi lights are automatically turned off when the landing gear is retracted The landing lights and taxi light power circuits are protected by 35-ampere and 15-ampere circuit  breakers,  respectively,  located  on  the  DC  power distribution   panel   beneath   the   aisleway   forward   of   the wing main spar. e. Ice Lights.  The ice lights circuit is protected by a 5-ampere  circuit  breaker  placarded  ICE  on  the  overhead circuit  breaker  panel  (fig.    2-7).    Control  of  the  lights  is provided by a switch placarded ICE - ON on the overhead control panel (fig.  2-13). 2-76.  INTERIOR LIGHTING. Lighting systems are installed for use by the pilot and copilot  The  lighting  systems  in  the  cockpit  are  provided with  intensity  controls  on  the  overhead  control  panel.    A switch placarded MASTER - ON, located on the overhead control panel in the COCKPIT LIGHT section (fig.  2-13), provides  overall  control  for  all  engine  instrument  lights, pilot's   and   copilot's   instrument   lights,   overhead   panel lights,   and   subpanel   lights.      The   switch   placarded   IR FLOOD ON, located on the overhead control panel (fig. 2- 13),     provides     overall     control     for     instrument     panel, glareshield, and pedestal extension/cockpit lights. a. Cockpit Lighting. (1)   Utility lights.   Two utility lights are located on the   cockpit   overhead   to   provide   additional   instrument panel 2-73