# SDR ASAA2021031334282

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 13, 2021
- Submitted: March 16, 2021
- Operation: Air carrier
- Aircraft: [N492AS](https://openairdocs.org/aircraft/N492AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 44110
- Aircraft time: 19,948 hours, 6,391 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Control Valve
- Part number: 3989085
- Part serial: 20455
- Condition: Faulted
- Location: Lt Zone Temp
- Part time: 9,098 hours, 2,713 cycles
- Stage of operation: TX
- 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/ASAA2021031334282

## Discrepancy

AFTER ENG START WITH MASTER RECALL, ZONE TEMP CAUTION LIGHT ILLUMINATED AND EXTINGUISHED WITH MASTER CAUTION RESET. GROUNDED - YES. CONFIRMED FAULT, PERFORMED BITE EST PER B737-900 FIM 21-62 TASK 801. FOUND HISTORY OF TCV FAULT. REMOVED & REPLACED TRIM AIR VALVE PER B737-900 AMM 21-61-21-400-801.

---
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.