# SDR ASAA2020121333689

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 13, 2020
- Submitted: December 16, 2020
- Operation: Air carrier
- Aircraft: [N479AS](https://openairdocs.org/aircraft/N479AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 60576
- Aircraft time: 19,279 hours, 6,149 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Valve
- Condition: Faulted
- Location: Cockpit Air
- 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/ASAA2020121333689

## Discrepancy

ZONE TEMP LIGHT ON RECALL ON AFTER START CHECK.  RESET W/MASTER CAUTION.  GROUNDED-YES.  VERIFIED DISCREPANCY.  PERFORMED PZTC BITE, REF B737-900 AMM 21-61-00.  FOUND "FLT DECK TRIM VALVE FAULTS" ON NR 2 PZTC.  RESET FAULT.  GROUND RAN BOTH PACKS, NO FAULTS LOGGED.  NO HISTORY IN 30 DAYS.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.