# SDR CALA2019030100329

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: February 28, 2019
- Submitted: March 1, 2019
- Operation: Air carrier
- Aircraft: [N68821](https://openairdocs.org/aircraft/N68821), registered now
- Make and model: Boeing 737924ER
- Aircraft serial: 43535
- Aircraft time: 17,441 hours, 6,267 cycles
- System (JASC): [2120 · Air Distribution System](https://openairdocs.org/jasc/2120)
- Part: Check Valve
- Condition: Unsecure
- Location: Ac Bay
- 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/CALA2019030100329

## Discrepancy

CABIN ALT LIGHT AND HORN CAME ON AT FL 220. FOUND GROUND AIR CONDITIONING CHECK VALVE OFF ITS HINGE ALLOWING PRESSURIZED AIR TO ESCAPE OVERBOARD. REPLACED FLAPPER DOOR/CHECK VALVE. DOOR SECURED AND OPERATES NORMALLY. REF AMM 21-21-01 PAGE 401. IPC REFERENCE # 21-21-01-01A.

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