# SDR ASAA2021030934268

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 9, 2021
- Submitted: March 12, 2021
- Operation: Air carrier
- Aircraft: [N491AS](https://openairdocs.org/aircraft/N491AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 44109
- Aircraft time: 19,970 hours, 6,401 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Valve
- Condition: Faulted
- Location: Zone Trim
- Stage of operation: IN
- How discovered: 9
- Nature of condition: J
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2021030934268

## Discrepancy

WHILE ACCOMPLISHING #1 PZTC BITE FOUND ZONE TRIM VALVE FAULT ON VERIFY. GROUNDED - YES. NO CURRENT FAULTS IN BACK SYSTEM. BITE CHECK RESET PROCEDURE CLEARED FAULT PER B737-900 AMM 21-51-00-700-803 AC OK FOR SERVICE.

---
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.