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A line mechanic reports about an MEL chapter 34-41 deferral procedure that requires pulling and collaring the weather radar circuit breaker on an A320 aircraft. Approximately five seconds later the terr (terrain) fault light illuminates in the overhead terr switch. No reference in the MEL about the fault light or potential effects on the egpws system.
| Attributes | |
| ACN | 919857 |
| Time | |
| Date | 201011 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Parked |
| Component | |
| Aircraft Component | Weather Radar |
| Person 1 | |
| Qualification | Maintenance Airframe Maintenance Avionics Maintenance Powerplant |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
MEL 34-41a; MEL 34-41b request weather radar circuit breaker to be pulled before flight. However; when the C/B is tripped and collared; about five seconds later the terrain fault light illuminates in the overhead terrain switch. The MEL does not direct maintenance to address this 'induced' light fault. Neither does the MEL inform the flight crew in their operations placard on the maintenance release that there will be a terrain fault displayed. The terrain function is truly faulted at this time because there is no response to any preflight requests by the crew or (centralized fault display system) cfds test by maintenance. This same flight deck effect happened on another A320 and was simulated on two other A320s.
Original NASA ASRS Text
Title: A Line Mechanic reports about an MEL Chapter 34-41 deferral procedure that requires pulling and collaring the Weather Radar circuit breaker on an A320 aircraft. Approximately five seconds later the TERR (Terrain) fault light illuminates in the overhead TERR switch. No reference in the MEL about the fault light or potential effects on the EGPWS system.
Narrative: MEL 34-41a; MEL 34-41b request Weather Radar circuit breaker to be pulled before flight. However; when the C/B is tripped and collared; about five seconds later the Terrain fault light illuminates in the overhead Terrain switch. The MEL does not direct Maintenance to address this 'induced' light fault. Neither does the MEL inform the flight crew in their operations placard on the Maintenance Release that there will be a Terrain fault displayed. The Terrain function is truly faulted at this time because there is no response to any preflight requests by the crew or (Centralized Fault Display System) CFDS test by Maintenance. This same flight deck effect happened on another A320 and was simulated on two other A320s.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.