EGPWS LINE MAINTENANCE MANUAL
3 FAULT ISOLATION (TROUBLESHOOTING)
3.1 GENERAL
The troubleshooting methods provided in this section identify system and sensor or subsystem faults to the lowest level possible. Additional fault isolation in the installation or associated sensors or subsystem should be performed using the aircraft installation and wiring diagrams and other supporting documentation in accordance with established maintenance procedures.
Do not remove or replace the EGPWC until all associated sensors or subsystems and their interfaces have been verified per established maintenance procedures and the fault is isolated to the EGPWC. If the troubleshooting methods determine that the EGPWC is faulty, then the EGPWC should be replaced per Section 6. Route the faulty EGPWC to an authorized repair facility for repair.
3.2 TROUBLESHOOTING GUIDE
In general, if any EGPWS Inoperative status is indicated, the EGPWC front panel LED’s should be checked. The following table shows the recommended maintenance action in response to the front panel LED’s.
EXTERNAL | COMPUTER | COMPUTER |
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FAULT | OK | FAIL | CORRECTIVE ACTION |
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OFF | GREEN | OFF | Normal operation. |
YELLOW | GREEN | OFF | Troubleshoot external faults using the Level 2 Self- |
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| Test. DO NOT REMOVE OR REPLACE THE EGPWC |
OFF | OFF | OFF | Ensure that the EGPWC is installed in the rack |
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| correctly and power to the EGPWC is turned on. |
OFF | OFF | RED | Record the Level 2 |
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| replace the EGPWC if required. |
OFF | GREEN | RED | Record the Level 2 |
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| replace the EGPWC if required. |
YELLOW | OFF | OFF | Troubleshoot external faults using the Level 2 Self- |
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|
| Test. DO NOT REMOVE OR REPLACE THE EGPWC |
YELLOW | OFF | RED | Troubleshoot external faults using the Level 2 Self- |
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| Test. Remove and replace the EGPWC if required. |
YELLOW | GREEN | RED | Record the Level 2 |
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| external faults using the Level 2 |
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| and replace the EGPWC if required. |
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A Terrain INOP light rarely implies an external or internal failure of the EGPWC. The Terrain INOP light may turn on if the required accuracy of the position information is not being received from the GPS, IRS, or the FMC. Therefore, if the Terrain INOP light is reported to be on (or was on), perform a Level 2
NOTE: The Computer Fail Light will illuminate during some ground test procedures that use the WinVIEWS Software utility, even although no fault exists. The EGPWS Computer Fail Light will extinguish after testing has completed.
The following sections detail the operation of the EGPWS
CAGE CODE: 97896 | SCALE: NONE SIZE: A DWG NO.: | REV: G | SHEET 23 of 68 |