# SDR UALA2011120106590

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 30, 2011
- Submitted: December 5, 2011
- Operation: Air carrier
- Aircraft: N174UA
- Make and model: Boeing 747422
- Aircraft serial: 24381
- Aircraft time: 85,083 hours, 9,544 cycles
- Engine: Pwa PW4056
- System (JASC): [2133 · Pressure Regulator/Outflow Valve](https://openairdocs.org/jasc/2133)
- Part: Outflow Valve
- Part number: 7159953
- Part serial: 150156
- Condition: Malfunctioned
- Location: Cabin Pressure
- Stage of operation: CR
- How discovered: C
- Nature of condition: L
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UALA2011120106590

## Discrepancy

DURING TEST FLIGHT, BOTH PRESSURE RELIEF VALVES DID NOT OPEN AT 9.5 PSID.  REPLACED BOTH PRESSURE RELIEF VALVES, OP CHECKED OK ON GROUND REF AMM.

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