TM 1-1510-223-10 Change 3          3-47 current vertical speed or to allow a new vertical speed to be selected with either the autopilot pitch wheel or by us- ing the touch control steering switch on the control wheel. When operating in the VS mode the ON placard located on the face of the switch will be illuminated and the target vertical speed will be displayed on the EADI. (9)    Altitude preselect mode switch-indicator. De- pressing  the  altitude  preselect  mode  switch-indicator, placarded ALT SEL, will command the flight control com- puter to arm and capture and maintain the altitude dis- played  on  the  altitude  preselector  (fig.  3-23).  When operating in the ALT SEL mode the ARM or CAP indica- tors  located  on  the  switch  face  will  be  illuminated  as appropriate. (10) Altitude hold mode switch-indicator. Depress- ing  the  altitude  hold  mode  switch-indicator,  placarded ALT, commands the flight control computer to hold the current altitude, and will illuminate the ON indicator lo- cated on the face of the switch. Capturing the altitude displayed on the altitude preselector will also cause the system to maintain that altitude. i. Control-Wheel  Mounted  Autopilot  Disconnection Switches.  A bi-level autopilot/electric trim/yaw damper disconnect switch, placarded DISC - AP & YD - TRIM, is mounted on each control wheel (fig. 2-22). Depressing the switch to the first level will disconnect the autopilot and the yaw damper. Depressing the switch to the sec- ond level will also disconnect the electric elevator trim. j. Touch  Control  Steering  (TCS).  A  control-wheel mounted touch control steering switch (fig. 2-22), plac- arded TCS, allows the pilot to manually change aircraft attitude, altitude, vertical speed, or airspeed without dis- engaging  the  autopilot.  The  TCS  switch  is  held  de- pressed  while  the  aircraft  is  maneuvered  to  the  new attitude, altitude, vertical speed, or airspeed. When the switch is released, the autopilot will automatically syn- chronize to the vertical mode. If an air data mode (IAS or VS) was selected, the selected value will be synchro- nized to the current value when the switch is released. k.   Go-Around Switch.  A pushbutton switch located on   the   left   power   lever   (fig.   2-12),   placarded   GO AROUND, activates the flight control system go-around mode when depressed. Go-around mode will disengage the autopilot, command a wings-level 7 degree nose-up attitude, and engage the yaw damper. l. Rudder Boost/Yaw Control Test Switch. A three- position toggle switch located on the pedestal extension (fig. 2-13), placarded RUDDER  BOOST - OFF - YAW CONTROL TEST, arms the rudder boost system and is used to test for correct  operation of the stability aug- mentation computer. m. Autopilot    EFIS    Select    Switch.    A   pushbutton switch-indicator  located  above  the  pilot’s  EADI,  plac- arded AP EFIS 1 and AP EFIS 2, selects which side’s symbol generator will provide inputs to the flight control computer. n.   Symbol Generator Reversionary Switch. WARNING Placing   the   pilot   and   co-pilot   reversionary switches to the REV position on the SYM GEN switch will cause the blanking of all four EFIS display screens. A   symbol   generator   reversionary   toggle   switch   (fig. 2-16), placarded SYM GEN, REV - NORMAL, is located on the left and right sides of the instrument panel. In the event of a known or suspected symbol generator failure, placing the symbol generator reversionary switch to the REV position connects the corresponding EFIS system to the cross-side symbol generator. In the reversionary position, the opposite side symbol generator provides all the information to both (all four) displays. Additionally, the opposite display controller controls all of the display func- tions. NOTE If the SYM GEN reversionary switch is moved to the REV position with the autopilot/flight director selected to that side, the flight director modes will disengage. Table 3-6 shows which flight director modes are reset by the EFIS when sources are changed. Table 3-6.  Flight Director Modes Reset when EFIS Sources Change Selection Action FD Modes Reset V/L or INS/TCN HDG ATT Navigation Lateral All modes NOTE: When ATT is selected, the autopilot also disen- gages. NOTE When ATT is selected, the autopilot will disen- gage. o.   Automatic Flight Control System - Check as fol- lows: 1.   MASTER  SWITCH  (overhead  control  panel, fig. 2-13) - ON. 2.   AVIONICS  MASTER  POWER  switch  (over- head  control  panel,  fig.  2-13)  -  ON  or  EXT PWR as required. 3.   #1 and #2 EFIS POWER switches (overhead control panel, fig. 2-13) - ON. 4.   AUTO PLT POWER switch (overhead control panel, fig. 2-13) - ON. 5.   RUDDER   BOOST/YAW   CONTROL   TEST switch (pedestal extension, fig. 2-12) - RUD- DER BOOST.