# SDR UIEA200700092

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 26, 2007
- Submitted: February 27, 2007
- Operation: Air carrier
- Aircraft: N523MC
- Make and model: Boeing 747-2D7B
- Registry model: [Boeing 747-2D7B](https://openairdocs.org/model/boeing-747-2d7b) (OpenAirDocs)
- Aircraft serial: 21782
- Aircraft time: 94,827 hours, 17,100 cycles
- System (JASC): [2150 · Cabin Cooling System](https://openairdocs.org/jasc/2150)
- Part: Relief Valve
- Part number: 3206257
- Part serial: 479
- Condition: Failed
- Location: A/C Pack
- Stage of operation: CL
- 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/UIEA200700092

## Discrepancy

DURING PASSING 3000' WHEN PACKS WERE TURNED ON DUCT PRESS LOW LIGHT ILLUMINATED.  DUCT PRESS 9 PSI.  ENGINE BLEED VALVES 2, 3 AND 4 OPEN.  REMOVED AND REPLACED NR 4 PRESS RELIEF VALVE.  LEAK CHECKED COMPLIED WITH, NO DEFECTS AT THIS TIME REF AMM 71-00-00.

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