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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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01/28/21

Message Overview:

TAWS SYSTEM FAIL
(Advisory)

DDG Reference: 34-42
Pilot Action (QRH): AVNC 02-38
System Description: 34-42-00
Schematic Diagram: 34-42-00
Wiring Diagram: 34-42-01
34-42-09

Message Description:

The cyan 'TAWS SYSTEM FAIL' advisory CAS message indicates the terrain awareness warning system has failed.

  • System self-test and MDC information could help isolate input validity or TAWS computer status prior to component replacement.
  • A system self-test of the EGPWS Computer could reveal the problem.
  • Also use the "System Information" link to the right for more information on using Winviews for system troubleshooting.

Possible Causes:

    • Terrain-Avoidance Warning System (TAWS) Computer (A34)

    • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-000-801
Installation of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-400-801
Removal of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-000-802
Installation of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-400-802
Operational Test of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-710-801
Operational Test of the Terrain-Avoidance Warning System (TAWS) Computer AMM 34-42-01-710-802
Removal of the Terrain-Avoidance Warning System (TAWS) Configuration Module AMM 34-42-03-000-801
Installation of the Terrain-Avoidance Warning System (TAWS) Configuration Module AMM 34-42-03-400-801
Removal of the TAWS/LANDING GEAR Control-Panel AMM 34-42-09-000-801
Installation of the TAWS/LANDING GEAR Control-Panel AMM 34-42-09-400-801
Operational Test of the TAWS/LANDING GEAR Control-Panel AMM 34-42-09-710-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02

Troubleshooting Recommendations:

Level 1: Go/No-Go Status. (Level 1) Press the GPWS test switch for less than 2 seconds. NOTE - Pressing the GPWS test switch for more than 2 seconds will active the Long Level 1 Self-Test (Go/NO GO plus all configured voices) Level 1 Self-Test provides Go/NO GO information. Refer to the applicable Ground Test procedure for expected enunciations in the Level 1 Self-Test. If the enunciations in the Level 1 Self-Test do not match the Ground Test procedure confirm the wiring of the program pins against the Aircraft Wiring Diagram and correct the wiring problem. If the Level 1 Self-Test enunciations indicate "INOP", proceed to
Level 2: Current Faults. (Level 2) Once the Level 1 Self-Test audio begins press the GPWS test switch for less than 2 seconds. Level 2 Self-Test provides enunciation of all internal and external faults existing at the time of the test request.
  • Internal Faults usually indicate a problem with the EGPWS. However,experience has shown most internal faults at initial installation are due to aircraft wiring errors. Internal faults on in-service installations are more often attributed to the EGPWS.
  • External Faults indicate a problem with a system providing input to the EGPWS. This mating system (and the wiring to it) should be verified.
Level 3: System Configuration. (Level 3) When the "PRESS TO CONTINUE" message is enunciated at the end of Level 2 Self-Test, press the GPWS test switch for less than 2 seconds. Mark V
Part Number, Mod Status, Serial Number, Application Software Version, Configuration Software Version, Terrain Database Version, Envelope Modulation Database Version, Boot Code Version, RAAS RCD Part Number (Only if a non-null RCD is loaded), Aircraft Type, Audio Menu, Altitude Call-out Menu, All other selected options from program pins.
Mark VII
Part Number, Mod Status, Serial Number, Application Software Version, Configuration Software Version, Terrain Database Version, Envelope Modulation Database Version, Boot Code Version, RAAS RCD Part Number (Only if a non-null RCD is loaded), Aircraft Type, AOA and Flap Type, Radio Altitude Type, Air Data Type, Attitude and Acceleration Type, Navigation Input Type, Position Input Type, Terrain Display Type, Altitude Call-out Menu, Volume Select, Audio Menu, IO Discrete Type, Optional Input Type, All other selected options from program pins.
Level 4: Fault History (Level 4) When the "PRESS TO CONTINUE" message is enunciated at the end of Level 3 Self-Test, press the GPWS test switch for less than 2 seconds. Annunciate the number of the most recent flight leg with faults as "FLIGHT X", where "X" is a number from 1 to 10 where 1 is the most recent flight leg. Annunciate any internal faults stored for leg X, Annunciate any external faults stored for leg X, Increment to next oldest leg with faults (if any) and repeat the above sequence.
Level 5: Warning History (Level 5) When the "PRESS TO CONTINUE" message is enunciated at the end of Level 4 Self-Test, press the GPWS test switch for less than 2 seconds. Annunciate the number of the most recent flight leg with alerts as "FLIGHT X", where "X" is a number from 1 to 10 where 1 is the most recent flight leg. Annunciate any alerts stored for leg X, Increment to next oldest leg with alerts (if any) and repeat the above sequence.
Level 6: Discrete Input Test (Level 6) When the "PRESS TO CONTINUE" message is enunciated at the end of Level 5 Self-Test, press the GPWS test switch for less than 2 seconds. The voice "DISCRETE INPUT TEST, PRESS TO CANCEL" will be enunciated every 60 seconds throughout the Level 6 Self-Test. Press the GPWS test switch for less than 2 seconds to end the test. Level 6 Self-Test provides any easy method to test discrete inputs (GND/Open or 28VDC/Open). If state changes occur on any discrete input (other than the Self-Test input) the EGPWS will annunciate the functional name of the discrete followed by its new state. For example, if the Glideslope Cancel discrete input is defined as GND = Cancel, and the EGPWS input transitions from Open to GND, Level 6 Self-Test will enunciate: "GLIDESLOPE CANCELED". Momentary discrete inputs must be held in the active state for a few seconds to hear both the active and inactive state enunciated.

Useful Tip - pressing the GPWS test switch for more than 2 seconds during Level 2 through 5 will bypass the test information an jump immediately to the end of that level ("PRESS TO CONTINUE" voice).

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