# SDR ASAA2021010433820

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 4, 2021
- Submitted: January 7, 2021
- Operation: Air carrier
- Aircraft: [N433AS](https://openairdocs.org/aircraft/N433AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 41704
- Aircraft time: 27,443 hours, 8,767 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989085
- Part serial: 29251
- Condition: Failed
- Location: Lt A/C Pack
- Part time: 12,311 hours, 3,821 cycles
- Stage of operation: NR
- How discovered: 9
- Nature of condition: J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021010433820

## Discrepancy

CONT CAB ZONE TEMP LIGHT ILLUMINATES ON RECALL.  GROUNDED-YES.  ACCOMPLISHED PACK/ZONE TEMPERATURE CONTROLLER BITE, PER B737-900 AMM 21-61-00-700-806-802, FLIGHT DECK TRIM VALVE FAILED.  REMOVED AND INSTALLED NEW CONTROL CABIN TRIM VALVE, PER AMM 21-61-21/401.  NO FAULTS FOUND.  GROUND VERIFICATION SUCCESSFUL.

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