TM 1-1510-224-10 CHAPTER 3 AVIONICS Section I.  GENERAL 3-1. INTRODUCTION. Except  for  mission  avionics,  this  chapter  covers  all avionics equipment installed in the RC-12P and RC-12Q aircraft.  It provides a brief description of the equipment, the   technical   characteristics,   and   locations.      It   covers systems and controls, and provides the proper techniques    and    procedures    to    be    employed    when operating  the  equipment.    For  more  detailed  operational information  consult  the  vendor  manuals  that  accompany the aircraft loose tools. 3-2. AVIONICS EQUIPMENT CONFIGURATION. The    aircraft    avionics    covered    consists    of    three groups   of   electronic   equipment.      The   communication group consists of the intercom system, UHF transceivers (2,   HAVEQUICK),   VHF-FM   transceiver   (SINCGARS), VHF-AM    transceivers    (2),    HF    transceiver,    and    an emergency   locator   transmitter   (ELT).      The   navigation group consists of VOR/localizer/glideslope/marker beacon  receivers  (2),  automatic  direction  finder  receiver (ADF), inertial navigation system (INS), TACAN receiver, a   global   positioning   system   (GPS),   a   radio   altimeter system,  a  gyromagnetic  compass  system,  an  electronic flight  instrument  system  (EFIS),  and  a  digital  integrated flight  control  system.    The  transponder  and  radar  group consists   of   a   weather   radar,   lightning   sensor   system, transponder, and a servoed encoding altimeter indicator. The transponder and radar group includes an identification,  position,  emergency  tracking  system,  and a radar and lightning sensor system to locate potentially dangerous   weather   areas.      For   additional   operational details    to    operate    equipment    'controlled    by    aircraft survivability equipment/avionics control system (ASE/ACS) refer to Chapter 4. 3-3. POWER SOURCE. a. DC     Power.          DC     power     for     the     avionics equipment  is  provided  from  four  sources:    the  aircraft battery,  left  and  right  generators,  and  external  power. Power  is  routed  through  two  50-ampere  circuit  breakers to  the  avionics  power  relay,  which  is  controlled  by  the AVIONICS   MASTER   POWER   switch,   located   on   the overhead  control  panel  (fig.    2-15).    Individual  system circuit  breakers  and  the  associated  avionics  buses  are shown in figure 2-9. (1) AVIONICS  MASTER  POWER  switch.    A switch placarded  AVIONICS MASTER POWER ON EXT PWR,  located   on   the   overhead   control   panel   controls power to the # 1 and # 2 avionics buses. (a) Off.    In  the  aft  (off)  position,  power from the 5-ampere circuit breaker placarded AVIONICS MASTER PWR,  located  on  the  overhead  circuit  breaker panel  (fig.    2-9),  energizes  the  avionics  relay,  removing power from the avionics buses. (b) ON.      With   the   switch   in   the    ON (center)    position,    the    avionics    power    relay    is    de- energized  and  power  is  applied  through  the  35-ampere AVIONICS  MASTER PWR # 1 and  #  2  circuit  breakers to    the    individual    avionics    circuit    breakers    on    the overhead circuit breaker panel (fig.  2-9). NOTE If    the    AVIONICS    MASTER    POWER switch  fails  to  operate,  power  to  the individual   avionics   circuit   breakers can   be   provided   by   pulling   the   5- ampere    circuit    breaker,    placarded AVIONICS  MASTER  CONTR,  located on the overhead circuit breaker panel (fig.  2-9). (c)External  power  (EXT  PWR).    When  the  switch  is  in the EXT PWR (forward) position, external power may be applied  to  the  avionics  buses.    The  avionics  system  is automatically isolated from  DC GPU power.  Setting the AVIONICS  MASTER  POWER  switch  to  the   EXT  PWR position allows avionics isolation from  DC GPU power to be  overridden,  de-energizing  the  avionics  power  relay, and  applying  power  to  the  avionics  equipment  from  the DC GPU. b. Single-Phase  AC  Power.      Two   static   inverters supply   400   Hz   single-phase   115   volt   and   26   volt   AC electrical   power   to   the   avionics   equipment.      During normal operation, the  # 1  inverter  supplies  115  volts  AC and  26  volts  AC  power  to  the  #  1  avionics  systems  and the  #  2  inverter  supplies  AC  power  to  the  #  2  avionics system. If   either   inverter   fails,   the   total   single-phase   AC electrical    load    is    shifted    to    the    remaining    inverter automatically    unless    a    ground    fault    exists.        Either inverter  is  capable  of  supplying  the  entire  AC  electrical load.      AC   power   from   the   inverters   is   routed   through fuses  located  in  the  nose  avionics  compartment.    The single   phase   inverters   are   controlled   by   two   switches placarded  # 1 and  #  2  1f  INVERTER  -  ON,  located  on the overhead control panel (fig.  2-15). c. Three-Phase    AC    Power.        Three    phase    AC electrical  power  for  operation  of  the  inertial  navigation system  and  mission  avionics  is  supplied  by  two  3000 volt-ampere,   solid   state,   three   phase   inverters.      The three phase 3-1