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EGPWS LINE MAINTENANCE MANUAL
CAGE CODE: 97896 SCALE: NONE SIZE: A DWG NO.: 060-4199-180 REV: G SHEET 32 of 68
NOTE: Before attempting to correct an external fault, verify that the EGPWS installation configuration matches the
aircraft configuration. If the installation configuration and aircraft configuration does not match, check the Program
Pin or Configuration Module connections being sure to cycle power to the EGPWC in the process. If an incorrect
aircraft configuration exists, the Program Pins must be changed or the Configuration Module may need to be
reprogrammed (see Maintenance Practices) or replaced (see Removal/Installation section).
If the unit is a MK V or MK VII with integral GNSSU (-060 part number), and external faults are indicated on GPS
signals (e.g., GPS BUS 1 LATITUDE FAULT), an internal fault may exist. In this case both fault lights will be on and
the message INTERNAL GPS FAULT will also be indicated. This condition can also be caused by a disconnected or
broken antenna wire. Ensure good antenna connection before replacing the EGPWS/GNSSU.
If no faults are detected, the following messages will be enunciated:
“CURRENT FAULTS”
“NO FAULTS”
“PRESS TO CONTINUE”
If no faults are detected, but the GPS or GNSSU are not navigating properly, navigation status messages may be
enunciated as follows:
“CURRENT FAULTS”
“NO FAULTS”
Navigation Status Messages “PRESS TO CONTINUE”
The list of possible navigation problems is listed in Table 3–6. In these instances, no fault lamps will be lit on the
unit, however, TERRAIN INOP or TERRAIN UNAVAILABLE will be indicated on the Flight Deck.
TABLE 3-6: LEVEL 2 SELF-TEST – NAVIGATION STATUS MESSAGES
THE FOLLOWING GPS STATUS MESSAGES ARE AVAILABLE IN LEVEL 2 SELF-TEST:
Enunciation:
“TERRAIN AWARENESS NO VALID LATITUDE”
Probable Cause: GPS/GNSSU has not acquired a sufficient number of satellites.
Action:
Remove aircraft from hanger and wait 5 to 20 minutes for the GPS/GNSSU acquire a
sufficient number of satellites. Verify cabling and antenna connection for the GPS/GNSSU.
Enunciation:
“TERRAIN AWARENESS NO VALID LONGITUDE”
Probable Cause: GPS/GNSSU has not acquired a sufficient number of satellites.
Action:
Remove aircraft from hanger and wait 5 to 20 minutes for the GPS/GNSSU acquire a
sufficient number of satellites. Verify cabling and antenna connection for the GPS/GNSSU.
Enunciation:
“TERRAIN INOP”
Probable Cause: GPS/GNSSU has not acquired a sufficient number of satellites.
Action:
Remove aircraft from hanger and wait 5 to 20 minutes for the GPS/GNSSU to acquire
sufficient number of satellites. Verify cabling and antenna connection for the GPS/GNSSU.
Description: “TERRAIN AWARENESS-POSITION ERROR”
Probable Cause:
GPS/GNSSU has not acquired a sufficient number of satellites
or ARINC [743A / 743] setting incorrect.
Action:
Remove aircraft from hanger and wait 5 to 20 minutes for the GPS/GNSSU to acquire
sufficient number of satellites. Verify cabling and antenna connection for the GPS/GNSSU.
Verify correct 743A / 743 configuration.
Enunciation:
“TERRAIN CLEARANCE FLOOR POSITION ERROR”
Probable Cause:
GPS/GNSSU has not acquired a sufficient number of satellites
or ARINC [743A / 743] setting incorrect.
Action:
Remove aircraft from hanger and wait 5 to 20 minutes for the GPS/GNSSU to acquire
sufficient number of satellites. Verify cabling and antenna connection for the GPS/GNSSU.
Verify correct 743A / 743 configuration.