# SDR UIEA2026091400877

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 14, 2026
- Submitted: September 15, 2026
- Operation: Air carrier
- Aircraft: [N851GT](https://openairdocs.org/aircraft/N851GT), registered now
- Make and model: Boeing 747-87UF
- Registry model: [Boeing 747-87UF](https://openairdocs.org/model/boeing-747-87uf) (OpenAirDocs)
- Aircraft serial: 37565
- Aircraft time: 61,114 hours, 9,498 cycles
- System (JASC): [2133 · Pressure Regulator/Outflow Valve](https://openairdocs.org/jasc/2133)
- Part: Outflow Valve
- Part number: 50E991
- Part serial: 508
- Condition: Faulted
- Stage of operation: CL
- 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/UIEA2026091400877

## Discrepancy

AFTER LEVEL OFF AT 340, SLOWLY LOST CABIN PRESSURISATION TO APPROX 10,900.  BOTH OUTFLOW VALVES VERIFIED CLOSED. DESCENDED AND RETURNED TO VCP.  TRANSFER TO DMI 259214 PER MEL 21-31-02A CAT C.  R & R LWR FWD CARGO OVERBOARD EXHAUST VALVE IAW AMM 21-26-17-000-801-002 & AIPC 21-26-51-32A. GROUND TEST PASS, NO FAULTS NOTED. THIS CLOSES DMI 259214, PLACARDS REMOVED.

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