# SDR ASAA2020092133215

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 21, 2020
- Submitted: September 24, 2020
- Operation: Air carrier
- Aircraft: [N491AS](https://openairdocs.org/aircraft/N491AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 44109
- Aircraft time: 18,655 hours, 5,967 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Control Valve
- Part number: 3989083
- Part serial: 10777
- Condition: Faulted
- Location: Cockpit Temp
- Part time: 44,769 hours, 13,635 cycles
- Stage of operation: NR
- 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/ASAA2020092133215

## Discrepancy

CONT CAB ZONE TEMP ILLUMINATES DURING MASTER CAUTION RECALL, EXTINGUISHES WITH MASTER CAUTION RESET.  GROUNDED-YES.  ACCOMPLISHED BITE CHECK OF NR 2 ZONE TEMP CONTROLLER, SHOWS FAULT TCV, REF B737-800 AMM 21-61-21/401.  REMOVED AND REPLACED FLIGHT DECK PRIMARY TEMP CONTROL VALVE.  OPS, LEAK, AND BITE CHECK GOOD.

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