TM 55-1510-220-10 (1) Three   phase   inverter   control   switch.      A three  position  switch  placarded  No.1  MSN  OFF  No.2 MSN INV, located on the mission control panel (fig.  4- 1), controls three phase inverter operation. (2) Three phase volt/frequency meter. A three phase   volt/frequency   meter,   mounted   on   the   mission control panel (fig.  4-1).  monitors output of the selected three    phase    inverter.        Frequency    (Hz)    is    normally displayed  on  the  meter.    To  read  voltage,  press  the button   located   in   the   lower   left   corner   of   the   meter. Each  of  the  three  phases  is  monitored  individually  by election   on   the   mission   AC   volt   frequency   and   load selector switch. (3) Three   phase   loadmeter      A   three   phase loadmeter    mounted  on  the  mission  control  panel  (fig. 4-1 ).  monitors inverter output level.  Each of the three phases   is   monitored   individually   by   selection   of   the mission A(' volt frequency and load selector switch. (4) Three phase A C off annunciator light.  An indicator   light   placarded   30   AC   OFF,   located   on   the misson annunciator panel (fig.  4-1), indicates   that   three   phase   AC   power   is   not   being supplied. (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  leading  edge just   outboard   of   the   engine   nacelle   (fig.      2-1).      The receptacle  is  installed  inside  the  wing  structure  and  is 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) External AC power annunciator Light.    An  annunciator  light  placarded  EXT  AC  PWR ON, located on the mission annunciator panel (fig.  4-1), indicates   that   an   AC   GPU   plug   is   mated   to   the   AC external power receptacle. (b) External   AC   power   control   switch. A  switch  placarded  AC  EXT  POWER,  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. a. Description.          Exterior    lighting    (fig.        2-28) consists of a navigation light on the top of the aft section of the vertical stabilizer, one navigation light on top and bottom of each wing tip pod, two strobe beacons, one on top of the vertical stabilizer and one on the underside of the fuselage center section, dual landing lights, one taxi light mounted on the nose gear assembly, a recognition light  located  in  each  wing  tip,  and  two  ice  lights,  one light    flush    mounted    in    each    nacelle,    positioned    to illuminate along the leading edge of each outboard wing. b. Navigation   Lights.      The   navigation   lights   are protected by a 5-ampere circuit breaker placarded NAV on   the   overhead   circuit   breaker   panel   (fig.      2-27). Control  of  the  lights  is  provided  by  a  switch  placarded NAV-ON on the overhead control panel (fig.  2-12). c.. Strobe  Beacons.    The  strobe  beacons  are  dual intensity   units.      They   are   protected   by   a   15   ampere circuit  breaker  placarded  BCN  on  the  overhead  circuit breaker   panel   (fig.      2-27).      Control   of   the   lights   is provided   by   a   switch   placarded   BEACON   -   DAY   - NIGHT (fig.  2-12).  Placing the switch in the DAY position will activate the high intensity white  section  of  the  strobe  lights  for  greater  visibility during   daytime   operation.      Placing   the   switch   in   the NIGHT position activates the lower intensity red section of the strobe lights. d. Landing/Taxi  Lights.    Dual  landing  lights  and  a single taxi light are mounted on the nose gear assembly. The     lights     are     controlled     by     switches,     placarded LANDING  and  TAXI,  located  in  the  LIGHTS  section  of the    pilot's    subpanel.        The    landing    light    circuit    is protected    by    a    5-ampere    circuit    breaker    placarded LANDING, located on the overhead circuit breaker panel (fig.    2-27).    The  taxi  light  circuit  is  protected  by'  a  5- ampere  circuit  breaker  placarded  TAXI,  located  on  the overhead circuit breaker panel (fig. 2-27).  Landing/Taxi lights are turned off when the landing gear is retracted. The   landing   lights   and   taxi   light   power   circuits   are protected by 35ampere and 15-ampere circuit breakers, respectively, located on the DC power distribution panel, beneath the cockpit floor. e. Ice Lights.  The ice lights circuit is protected by a    5-ampere    circuit    breaker    placarded    ICE    on    the overhead circuit breaker panel (fig.  2-27). Change 2    2-68