# SDR ASAA2012121893480

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 18, 2012
- Submitted: December 20, 2012
- Operation: Air carrier
- Aircraft: [N592AS](https://openairdocs.org/aircraft/N592AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35190
- Aircraft time: 18,721 hours, 5,966 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989083
- Part serial: 10403
- Condition: Malfunctioned
- Location: A/C Bay
- Part time: 18,742 hours, 5,971 cycles
- Stage of operation: AP
- How discovered: O
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2012121893480

## Discrepancy

AFT CABIN ZONE TEMP LIGHT ON FINAL APPROACH, LIGHT EXTINGUISHED ON MASTER CAUTION RESET.  REPLACED AFT CABIN TRIM AIR VALVE IAW AMM 21-61-21. PERFORMED ZONE BITE TEST OF BOTH CONTROLLERS IAW 21-61-00, ZONE TRIM FAULT LIGHT EXTINGUISHED & BOTH OPS NORMAL.  AFT CABIN ZONE TEMP ANNUNC IN COCKPIT NO LONGER ILLUMINATES W/MASTER DIM RECALL.  RAN BOTH ACFT SYSTEMS IAW AMM 21-61-21 & PERFORMED LEAK CHECK IN AREA OF REPLACED TRIM VALVE, NO LEAKS NOTED. GROUND VERIFICATION SUCCESSFUL.

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