TM 55-1520-240-T
118-1.3 GLOBAL POSITIONING SYSTEM VISUAL CHECK (Continued)
18-1.3
13.Set the GPS CDU Data switch (10) to STAT. Lift
switch guard and toggle the Zeroize switch (17).
14.Set the GPS CDU DATA switch (10) to STAT.
Insert a Data Loader Module which contains
almanac information into the Data Loader
Receptacle (19) located on shelf five of the cabin
avionic/electronic compartment. Leave in for at
least 20 seconds, then remove Data Loader
Module.
15.With the GPS CDU Data switch (10) still at STAT,
slew (11) down to page 2 and compare the
Almanac Age located on display (6) line 2 with the
age recorded earlier in step 7.
16.Turn the GPS CDU Mode switch (7) to OFF.
Leave OFF for a few minutes then turn back ON
with the Mode switch (7) in the NAV position.
17. Stop APU. Refer to task 15-1.4.
FOLLOW-ON MAINTENANCE:
TM 55-1520-240-23:
Battery Disconnected
Electrical Power Off
The CDU data display (6), line 2 shall display
ZEROED. If ZERO FAIL is displayed, go to task
181.12.
No error messages shall be displayed on the CDU
data display (6). If an error message is displayed, go
to task 18-1.6.
The two values shall be different if the Almanac
stored in the Data Loader Module has been
successfully loaded into the GPS system. If the
Almanac Age is the same as before loading data with
the Data Module, go to task 18-1.8.
After warmup and test completion, GNAV shall
appear on CDU data display (6) line 1. This means
that the previously loaded almanac has been stored
by the GPS receiver (9). If COLD appears on CDU
data display (6) line 1 instead, go to task 18-1.13.
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