TM 1-1510-223-10 CHAPTER 3 AVIONICS Section I.  GENERAL 3-1. INTRODUCTION. Except  for  mission  avionics,  this  chapter  covers  all avionics  equipment  installed  in  the  RC-12N  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, HAVE   QUICK),   VHF-FM      transceiver   (SINCGARS), VHF-AM    transceivers    (2),    HF    transceiver,    and    an emergency  locator  transmitter  (ELT).    The  navigation group    consists    of    VOWR    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  served  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   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.  2-13).    Individual  system circuit  breakers  and  the  associated  avionics  buses  are shown in figure 2-7. (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.  2-7),  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 MAS- TER PWR # 1 and #2 circuit breakers to    the    individual    avionics    circuit    breakers    on    the overhead circuit breaker panel (fig. 2-7). 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. 2-7). (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 1li INVERTER - ON, located on the overhead control panel (fig. 2-13). 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, 3-1