# SDR ASAA2022031637701

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 16, 2022
- Submitted: March 19, 2022
- Operation: Air carrier
- Aircraft: [N448AS](https://openairdocs.org/aircraft/N448AS), registered now
- Make and model: Boeing 737990ER
- Aircraft serial: 36356
- Aircraft time: 20,764 hours, 6,554 cycles
- System (JASC): [2150 · Cabin Cooling System](https://openairdocs.org/jasc/2150)
- Part: Control Valve
- Part number: 633967541
- Part serial: 302
- Condition: Faulty
- Location: Right Ecs Bay
- Part time: 20,763 hours, 6,554 cycles
- Stage of operation: NR
- How discovered: O
- Nature of condition: O
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2022031637701

## Discrepancy

SAME ISSUE AS LO 60259389 +/-3 PSI DUCT PRESSURE OSCILLATION AND CABIN RATIO OSCILLATION +/-3. GROUNDED - YES. C/W PACK FLOW TEMPERATURE CONTROLLER BITE REF B737-900 AMM 21-61-00-740-801-002, NO EXISTING FAULTS FOUND, HISTORY SHOWS FLOW CONTROL VALVE FAULT # 21-51253. NO HARD FAULTS NOTED. REPLACED RIGHT PACK FLOW SENSOR PER AMM 21-51-43, OPS AND LEAK CHECK OK. REMOVED AND REPLACED RIGHT FLOW CONTROL AND SHUTOFF VALVE PER AMM 21-51-01-000-807-003 / 21-51-01-400-806-003. OPS CHECKED AND LEAK CHECKED GOOD.

---
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.