TM 55-1520-240-T 18-1.3    GLOBAL POSITIONING SYSTEM VISUAL CHECK (Continued) 18-1.3 INITIAL SETUP: Applicable Configurations: All Tools: Electrical Repairer's Tool Kit, NSN 5180-00-323-4915 Materials: None Personnel Required: Aircraft Electrician (2) TASK CHECK CIRCUIT BREAKERS 1.  Check that the following circuit breakers on No.  2 pdp are closed: GPS RCVR (1) GPS CONT (2) 2.  Start APU.  Refer to task 15-1.4. CHECK GPS CDU C- 11702/UR 3.  Turn aircraft CTR CSL LTG control (3) clockwise and counterclockwise while checking CDU (4) panel lighting. 4.  Turn   the   CDU   (4)   BRT   control   (5)   clockwise   and counterclockwise  while  checking  the  CDU  data  display screen (6) intensity level. 5.  Turn CDU Mode Switch (7) to TEST. CHECK GPS RECEIVER R-2400( )/A 6.  Check  the  time  totalizing  meter  (8)  on  front  panel  of GPS receiver (9). References: TM 11-1520-240-23 TM 11-5826-308-12 TM 55-1520-240-23 Equipment Condition: TM 55-1520-240-23: Battery Connected Hydraulic Power Off Global Positioning System Visual Check Performed (Task 18-1.2) RESULT If any circuit breaker (1 through 2) is open, close it. APU ON capsule shall come on. CDU (4) panel light shall vary with the changing setting of the aircraft dimmer control (3).    If  CDU  (4)  panel  light  is not  visible  or  intensity  level  does  not  vary  with  aircraft dimmer control (3) refer to TM 55-1520-240-T-2, Chapter 9. CDU data display screen (6) intensity level shall vary with the  changing  setting  of  the  CDU  BRT  control  (5).    If  no display appears or intensity level does not vary, go to task 18-1.4. After a 30-second warm-up the CDU data display (6) shall display data.   If failure data is displayed instead of TEST IN PROG, go to task 18-1.6.   After the test is completed TEST COMPLETE shall be displayed on line 1 and TEST OK shall be displayed on line 2 of the CDU data display (6).   If failure data is displayed, go to task 18-1.6. The  pointer  on  the  left  side  of  the  time  totalizing  meter window shall have an up/down movement. If no up/down movement, go to task 18-1.5. TASK CHECK GPS SYSTEM OPERA TION NOTE Continue  with  the  following  checks  only after the Start-up procedures given in TM 11-5826-30812   or   local   directives   have been  completed  (for  a  COLD  start)  and the  GPS  System  is  tracking  4  satellites. The  Mode  switch  (7)  shall  be  positioned on NAV. 7.  With 4 satellites being tracked and the Figure of Merit (FM)  being  5  or  less,  set  the  Data  switch  (10)  on  the CDU (4) to STAT.  Slew (11) down to page 2 and write down   the   Almanac   Age   displayed   on   line   2   (ALM followed by numbers).  Information will be needed later. 8.  Depress the GPS Alert Indicator (18). 9.  With the Data switch (10) of the CDU set to MSN, slew (11)  down  to  page  2.    Press  line  select  key  two  (12) until THRESH:  ENRT is displayed.  Enter a figure of merit on display (6) line three at least one level below the existing GPS system figure of merit (FM) displayed on line 1. 10.Depress the GPS/DOP lenses (13) on each of the two HSI  Mode  Select  Panels  (14)  (one  each  in  pilot  and copilot instrument panels). 11.Set the Data switch (10) of the CDU set to VARDTM. Enter at least one known waypoint.  Set the Data switch (10)   to   POS   and   call   up   the   waypoint   previously entered. 12.Connect  a  KYK-13  fill  device  to  the  KYK/GPS  Fill  J1 connector (15).  Set the GPS CDU  Data switch (10) to STAT.    Set  the  fill  device  Address  Select  switch  to desired setting and the Mode switch to ON.  Press and release the aircraft's INIT LOAD switch (16). RESULT If 4 satellites cannot be tracked, go to task 18-1.7. The GPS Alert Indicator (18) shall illuminate.  If indicator does not illuminate, go to task 18-1.10. The GPS Alert Indicator (18) shall illuminate.  If indicator does not illuminate, go to task 18-1.10. The  SEL  indication  at  the  lower  half  of  each  GPS/DOP (13) lens shall be illuminated.  If SEL not illuminated, go to task 18-1.11. The  number  one  needle  (20)  of  each  HSI  indicator  (25) shall  swing  to  show  the  bearing  to  the  station  with  the course deviation bar (21) centered.    The Range (22) and Course   (23)   readouts   shall   also   be   accurate.      If   the number one needle (20) does not swing to show bearing to the  station  or  the  Range  (22)  and  Course  (23)  readouts are not accurate, go to task 18-1.11. Successful   loading   of   keys   shall   be   indicated   by   the flashing  of  the  aircraft's  LOAD  STATUS  indicator  lamp (24)   within   approximately   5   seconds   of   pressing   the aircraft's INIT LOAD switch.   If lamp (24) does not flash, go to task 18-1.9.      Observe  the  GPS  CDU  data  display (6).   If an error message is present, go to task 18-1.6. GO TO NEXT PA GE Change 18  18-15