# SDR USMS20110907001

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 7, 2011
- Submitted: September 9, 2011
- Operation: General aviation
- Aircraft: [N950NS](https://openairdocs.org/aircraft/N950NS), registered now
- Make and model: Doug DC-9-83
- Registry model: [Doug DC-9-83](https://openairdocs.org/model/douglas-dc-9-83) (OpenAirDocs)
- Aircraft serial: 53023
- Engine: Pwa JT8D219
- System (JASC): [2131 · Cabin Pressure Controller](https://openairdocs.org/jasc/2131)
- Part: Controller
- Part number: 21184901
- Part serial: 91A0058
- Condition: No Test
- Location: Cabin Pressure
- 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/USMS20110907001

## Discrepancy

DURING CRUISE, HEARD A LOUD POP, FOLLOWED BY RAPID DECOMPRESSION OF CABIN. R & R OUTFLOW VALVE ACTUATOR, IAW AMM, OPS CHECKED GOOD.  R & R CABIN PRESSURE SELECTOR IAW AMM FOUND NR1 CABIN PRESSURE CONTROLLER FAILED BITE TEST.  SWAPPED NR1 & NR2 PRESSURE CONTROLLERS PROBLEM FOLLOWED. R & R NR 2 PRESSURE CONTROLLER IAW AMM.  PRESSURIZED CABIN TO VERIFY INTERGITY AND FOUND NO LEAKS IAW AMM.

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