TM 55-1510-219-10 NOTE The   INS   can   provide   test   signals   to   the Horizontal    Situation    Indicator    (HSI)    and connected  displays.    Pressing  TEST  switch during Standby, Align, or NAV mode causes all  digits  on  connected  digital  displays  to indicate   "8's,"   and   lights   the   HSI   and   the ALERT lamp.  Additional HSI test signals are provided   when   INS   is   in   Align   and   data selector    is    at    any    position    other    than DSRTK/STS. Under those conditions, pressing TEST switch causes HSI to indicate heading, drift angle, and track angle error all at   "0°"   or   "30°."   At   the   same   time,   cross track deviation is indicated at "3.75" nautical miles    (one    dot)    right    or    left    and    INS- controlled HSI flags are retracted from view. NOTE Output    test    signals    are    supplied    to    the autopilot    when    INS    steering    is    selected. Rotating   AUTO/MAN   switch   to   AUTO   and pressing  TEST  during  Align  furnishes  a  15° left   bank   steering   command.      A   15°   right bank  steering  command  is  furnished  when AUTO/MAN switch is set to MAN. NOTE The quick test procedure may be performed any time after Alignment State "8" is reached and prior to entry into NAV. 1.    Mode selector ALIGN. (Observe CDU displays are illuminated.) 2.    Data            selector            DSRTK/STS (monitor    right    data    display    until State   "8"   (or   lower)   is   reached.) (Observe right data display is ---N4, where "N" is not "9".) 3.    AUTO/MAN switch MAN. 4.    INS   Couple   to   flight   director   and autopilot, as applicable. 5.    Data   selector   Set   to   any   position except DSRTK/STS. 6.    TEST switch Press and hold. NOTE After    performing    the    preceding step, observe: MSU All lamps illuminated. CDU All lamps illuminated.  All "8's" displayed. HSI All angles 30°.  Cross-track devia- tion bar is one dot right.  All INS flags are retracted. Flight Director/ A  15°  steering command is is- Autopilot sued. Mission Control LINK  UPDATE   annunciated. Panel TACAN UPDATE annunciated. 7.    CDU  TEST  switch  Hold  depressed, and    rotate    AUTO/MAN    switch    to AUTO. (Observe all indications are as in step (6) except a 15' left steering command is issued.  On HSI, All angles are "0°" and cross-track deviation bar is one dot left.) 8.    CDU    TEST    switch    Release.        If desired, decouple INS. (Observe operation returns to normal.) NOTE Prior to pressing INSERT/ADVANCE pushbutton, any incorrectly loaded data can be corrected by pressing CLEAR pushbutton and reloading correct data. NOTE While parked aircraft is undergoing alignment,   encoding   altimeter   will   supply the field elevation (aircraft altitude) into INS. NOTE Once   present   position   has   been   inserted and   computer   has   advanced   to   alignment state     "7",     present     position     cannot     be reinserted   without   downmoding   to   STBY and restarting alignment. NOTE If   longitude   and   latitude   coordinates   are being used, skip step 8 (a) and proceed with step 8 (b). (a) Insert  UTM  coordinates  of  aircraft present position: 1.    Data selector UTM POS. (Observe     that     prior     to     initial     load,     INSERT/ ADVANCE pushbutton light illuminates.) 3-50