# SDR UIEA2023021700131

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 17, 2023
- Submitted: February 20, 2023
- Operation: Air carrier
- Aircraft: [N480MC](https://openairdocs.org/aircraft/N480MC), registered now
- Make and model: Boeing 747422
- Aircraft serial: 28812
- Aircraft time: 78,581 hours, 9,126 cycles
- System (JASC): [3500 · Oxygen System](https://openairdocs.org/jasc/3500)
- Part: None
- Condition: None
- Stage of operation: CR
- How discovered: V
- Nature of condition: J, O
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/UIEA2023021700131

## Discrepancy

CREW OXYGEN DROPPED FROM 1500-400 PSI IN 7 HOURS(<P><SPAN STYLE="COLOR: BLACK;">LEAKING B-NUT FITTING FOUND AT REGULATOR AND RETORQUED IAW AMM 20-51-01, NO CHANGE IN O2 PRESSURE IN 7 HOURS. ULTRASONIC LEAK CHECK COMPLETE, NO LEAKS NOTED. A/C PRESSURIZED, NO LEAKS NOTED.</SPAN></P>)

---
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.