Honeywell MK XXII, MK VIII manual Egpws Line Maintenance Manual, Description, “Terrain Inop”

EGPWS LINE MAINTENANCE MANUAL

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:

Probable Cause:

Action:

Enunciation:

Probable Cause:

Action:

Enunciation:

Probable Cause:

Action:

Description:

Probable Cause:

Action:

Enunciation:

Probable Cause:

Action:

“TERRAIN AWARENESS NO VALID LATITUDE”

GPS/GNSSU has not acquired a sufficient number of satellites.

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.

“TERRAIN AWARENESS NO VALID LONGITUDE”

GPS/GNSSU has not acquired a sufficient number of satellites.

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.

“TERRAIN INOP”

GPS/GNSSU has not acquired a sufficient number of satellites.

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.

“TERRAIN AWARENESS-POSITION ERROR”

GPS/GNSSU has not acquired a sufficient number of satellites or ARINC [743A / 743] setting incorrect.

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.

“TERRAIN CLEARANCE FLOOR POSITION ERROR”

GPS/GNSSU has not acquired a sufficient number of satellites or ARINC [743A / 743] setting incorrect.

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.

CAGE CODE: 97896 SCALE: NONE SIZE: A DWG NO.: 060-4199-180 REV: G SHEET 32 of 68