# SDR ASAA2021012433942

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 24, 2021
- Submitted: January 27, 2021
- Operation: Air carrier
- Aircraft: [N508AS](https://openairdocs.org/aircraft/N508AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35691
- Aircraft time: 45,601 hours, 13,520 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Modulating Valve
- Part number: 3989085
- Part serial: 20949
- Condition: Faulty
- Location: Lt A/C Pack
- Part time: 21,074 hours, 7,535 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/ASAA2021012433942

## Discrepancy

CONT CAB ZONE TEMP CAUTION ILLUMINATES ON RECALL AND EXTINGUSHES WITH MASTER CAUTION RESET.  GROUNDED-YES.  TASK CARD COMPLIED WITH PERFORMED PACK TEMP CONTROL VALVE BITE PROCEDURE, REF B737-800 FIM 21-62 TASK 801 ON NR 2 CONTROLLER.  FAULT SHOWED FLT DECK TRIM VALVE.  REMOVED AND INSTALLED NEW CONTROL CABIN TRIM VALVE, PER B737-800 AMM 21-61-21.  OPERATIONS CHECK GOOD, LEAK CHECK NOT DETECTED, TEMP CONTROL VALVE BITE PROCEDURE APPEARS ALL GREEN ON NR 2 CONTROLLER THIS CLEARS MEL 21-21G.  PLACARD AND CN REMOVED.  SEAMC SCOTT NOTIFIED.

---
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.