TM 1-1510-223-10 3-22           Change 3 The pilot’s and copilot’s symbol generators are the fo- cal point of information flow in the systems. The symbol generator converts information to video and deflection formats required by the EADI and EHSI displays, and provides analog steering information to the flight director/ autopilot interfaces. When engaged and coupled to the flight director com- mands,  the  digital  integrated  flight  control  system  will control the aircraft using the same commands displayed on the EADI. When engaged and not coupled to the flight director  commands,  manual  pitch  and  roll  commands may be inserted using the touch control steering (TCS) switch on the pilot’s or copilot’s respective control wheel or the autopilot pitch wheel and turn knob located on the pedestal extension. 3-16.   ATTITUDE AND HEADING REFERENCE SYS- TEM. The attitude and heading reference system consists of the vertical gyros (VG-14A), directional gyros (C-14A), dual    remote    compensator    (CS-412),    flux    valves (FX-220), and the inertial navigation system (INS). The vertical gyros provide the digital flight control sys- tem, electronic flight instrument system, and weather ra- dar antenna with pitch and roll information. The inertial navigation system, when selected for dis- play on the EFIS, also provides inputs to the flight control computer. The directional gyros, with the flux valve and compen- sator,   provide   stabilized   magnetic   north   referenced heading information for use by the digital flight control computer, electronic flight instrument system, INS, and mission equipment. 3-17.   AIR DATA SYSTEM (ADZ-800). The air data system consists of the digital air data computer (AZ-800), pilot’s barometric altimeter (BA-141), and the altitude preselector (AL-801). The  digital  air  data  computer  is  a  microprocessor- based digital computer which accepts both analog and digital  inputs,  performs  digital  computations,  and  sup- plies both digital and analog outputs. It receives both pitot and static pressure for computing standard air data func- tions. Altitude preselect data is input from the altitude preselector. Information from the digital air data comput- er  is  sent  to  the  pilot’s  barometric  altimeter  indicator, transponder, flight director/autopilot, INS, and GPS. 3-18.   ELECTRONIC FLIGHT INSTRUMENT SYSTEM (EFIS). a.   Description. The electronic flight instrument sys- tem consists of the pilot’s and copilot’s electronic attitude director indicators (EADI) and electronic horizontal situa- tion  indicators  (EHSI)  display  units  (ED-800),  symbol generators (SG-805), display controllers (DC-811), and instrument remote controllers (RI-106S). The EFIS electronic displays present pitch and roll at- titude,   heading,   course   orientation,   flight   path   com- mands,   radio   altitude,   weather   radar   and   lightning sensor system presentations, and mode and source an- nunciations. b.   Electronic  Flight  Instrument  System  (EFIS)  Pre- flight Test. NOTE For this test to be valid, the AUTO PLT POWER switch and the RADIO ALTIMETER switch must be ON. 1.   TEST switch (display controller, fig. 3-8) - De- press and hold. 2.   Verify the following indications on the EADI: a.   Radio Altimeter - Slews to 100 +/-10 feet. b.   DH replaced with dashes. c.   Marker beacon symbology appears. d.   HDG and ATT annunciators appear. e.   ATT FAIL annunciator appears in the cen- ter. f.   Pitch and roll command cue (artificial hori- zon) - out of view. g.   Runway cue drops from center. h.   GS and localizer off flags (Red X) appear. i.   TEST will appear in the upper left corner to indicate that the flight director mode se- lector lamp is good. 3.   Verify the following on the EHSI. a.   DTRK,  NM,  GSPD,  and  HDG  replaces with dashes. b.   HDG FAIL annunciator appears. c.   Course indicator and glidescope off flags appear. 4.   AP disconnect horn sounds after 5-7 seconds. 3-19.   DISPLAY CONTROLLER (DC-811). a.   Description. The display controller (fig. 3-8), en- ables each pilot to control formatting on his respective EHSI and EADI, and to select the source of navigation, attitude, and heading information. b.   Display Controller Controls, Indicators, and Func- tions: (1)    Full/Map   pushbutton   selector   switch.   The FULL/MAP pushbutton selector switch is a multiple func- tion switch that allows selecting the format of the EHSI.