# SDR UIEA2020070761489

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: July 6, 2020
- Submitted: July 7, 2020
- Operation: Air carrier
- Aircraft: [N493MC](https://openairdocs.org/aircraft/N493MC), registered now
- Make and model: Boeing 747-47UF
- Registry model: [Boeing 747-47UF](https://openairdocs.org/model/boeing-747-47uf) (OpenAirDocs)
- Aircraft serial: 29254
- Aircraft time: 88,915 hours, 14,368 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Valve
- Part number: 7520002
- Part serial: 920414
- Condition: Malfunctioned
- Location: Trim Air
- Stage of operation: CR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UIEA2020070761489

## Discrepancy

LOST ALL TARGET TEMPS EXCEPT F/D. ALL TEMPERATURE ZONES INCREASING AND DECREASING ERRATICALLY.  REMOVED AND REPLACED MASTER TRIM AIR PRESSURE REGULATING AND SHUT OFF VALVE IAW AMM 21-61-08 & 1. MASTER TRIM AIR VALVE TRIPPING C/B. CLEARED

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