18-3.3   DOPPLER/GPS   NAVIGATION   SYSTEM   OPERATIONAL   CHECK   (Continued) TASK RESULT TM  55-1520-240-T 1 8 - 3 . 3 TASK RESULT 7. Depress GPS Alert Indicator (7). 8. Place CDU DISPLAY switch (9) to PP. 9. Perform  the  following  for  downloading  of waypoints  from  Data  Loader  Cartridge: a. Place CDU (3) MODE switch (4) to OFF b. Insert  a  programmed  Data  Loader  in Receptacle  (8). c. Set  CDU  Mode  switch  to  MGRS. d. Make sure Mode of the GPS is in M. e. Set  CDU  Display  switch  to  WIND UTC/DATA. f. Depress  ENT  twice  to  display  the selection  menu. g. Enter 4 to select the data load page. h. To  begin  downloading,  depress  KYBD and  enter  “Y”  (yes). 10.  Turn CDU (3) MODE switch (4) to OFF, remove Data loader cartridge from the receptacle and turn the MODE switch (4) to MGRS. 11. Turn CDU (3) DISPLAY switch to (9) DIST/ BRG/TIME  and  select  several  waypoints. 12.    Depress the GPS/DOP lenses (10) on each of The SEL indication at the lower half of each GPS/DOP the two HSI Mode Select Panels (11) (one each (8) lens shall be illuminated. If SEL not illuminated, go in pilot and copilot Instrument panels). to  TM  11-1520-240-23. 13.  Observe  each  HSI  (12). The number one needle (13) of each HSI indicator (12) shall swing to show the bearing to the station with the course  deviation  bar  (14)  centered.  The  Range  (15) and Course (16) readouts shall also be accurate. If the number one needle (13) does not swing to show bear- ing to the station or the Range (15) and Course (16) readouts are not accurate, go to TM 11-1520-240-23. GPS Alert Indicator (6) illuminates. If indicator does not illuminate, go to task 18-3.7. 14. Present position is displayed. If present position is not displayed, go to task 18-3.8. 15. CDU (3) displays DOWNLOAD WAYPTS IN PRO- CESS  and  WAIT  ACK  during  waypoint  loading  and DOWNLOAD  WAYPTS  COMPLETE  within  one  minute to indicate that waypoint loading is complete. If display is incorrect go to task 18-3.9. 16. 17. 18. 19. Observe  each  HSI  (12)  and  four-line  display on the CDU (3). In  the  center  instrument  panel  switch  GPS ZEROIZE  switch  (17)  up  then  down.  On  the CDU  (3)  set  DISPLAY  switch  to  DIST/BRG/ TIME  and  observe  the  four-line  display. Reperform steps 8, 9 and 10 above. Perform  HAVEQUICK  checks  on  the  HF,  UHF and  SINCGARS  Radio  Sets. Turn CDU (3) MODE switch (4) to OFF. Stop APU. Refer to task 15-1.4. The indications on the four-line display and each HSI are the same. If the indications are not the same, go to task  18-3.10. All  waypoints  have  disappeared.  If  waypoints  have  not disappeared, go to task 18-3.11. This task shows that the system is functional and ready. If waypoints could not be downloaded, go to task  18-3.9. The Radio Sets have HAVEQUICK Timing. If any or all Radio Sets do not have HAVEQUICK Timing go to task  18-3.12 The  Doppler/GPS  Navigation  System  is  off. FOLLOW-ON   MAINTENANCE: TM   55-1520-240-23: Battery  Disconnected Electrical Power Off The four-line display will display distance, bearing and time information for each waypoint. If any four-line dis- play is incorrect, replace the CDU. GO  TO  NEXT  PAGE 18-71 Change   19