# SDR IPXA2021121576977

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 14, 2021
- Submitted: December 15, 2021
- Operation: Air carrier
- Aircraft: [N581UP](https://openairdocs.org/aircraft/N581UP), registered now
- Make and model: Boeing 747-44AF
- Registry model: [Boeing 747-44AF](https://openairdocs.org/model/boeing-747-44af) (OpenAirDocs)
- Aircraft serial: 25866
- Aircraft time: 119,231 hours, 19,948 cycles
- System (JASC): [2612 · Fire Detection](https://openairdocs.org/jasc/2612)
- Part: Fire Bottle
- Condition: Low Pressure
- Location: Apu Bay
- Stage of operation: CR
- 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/IPXA2021121576977

## Discrepancy

APU FIRE MASTER WARNING DISPLAYED FOR 5 SECONDS AT FL410. THE WARNING EXTINGUISHED WITHOUT INTERVENTION. AS A PRECAUTION WE RAN APU FIRE CHECKLIST PROCEDURE AND DISCHARGED THE APU FIRE BOTTLE. STATUS LEVEL MESSAGES "BOTTLE LOW APU" AND "APU.   REMOVED APU FIRE BOTTLE & INSTALLED A SERVICEABLE BOTTLE IN REF TO MM CH 26-22-01. OPS CKS OK. EFF SOURCE REF IPC 26-22-01-02-060.

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