# SDR MJYA20251121013

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 21, 2025
- Submitted: November 24, 2025
- Operation: Air carrier
- Aircraft: [N783TW](https://openairdocs.org/aircraft/N783TW), registered now
- Make and model: Doug DC-9-15F
- Registry model: [Doug DC-9-15F](https://openairdocs.org/model/mcdonnell-douglas-dc-9-15f) (OpenAirDocs)
- Aircraft serial: 47010
- Aircraft time: 59,152 hours, 67,297 cycles
- System (JASC): [2160 · Cabin Temperature Control System](https://openairdocs.org/jasc/2160)
- Part: Butterfly Valve
- Part number: 32185831
- Part serial: P1312
- Condition: Stuck
- Location: Zone 100
- Stage of operation: CR
- How discovered: O
- Nature of condition: J
- Precautionary procedure: B
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/MJYA20251121013

## Discrepancy

TWO HOURS INTO CRUISE AT FL 350 ENCOUNTERED A LOSS OF CABIN PRESSURE.  RAN COM PROCEDURES CABIN ALTITUDE WARNING/RAPID DEPRESSURIZATION.  CABIN RECOVERED AND HELD AT 8500 FEET FOR ABOUT 20 MIN BEFORE A RAPID SPIKE IN CABIN CLIMB (FULL SCALE)  INITIATED AN EMERGENCY DESCENT WITH ATC.  CABIN DID NOT RECOVER FOR REMAINDER OF FLIGHT.  DIVERTED TO KABQ.  CORRECTIVE ACTION - LOG PAGE 78763 - 11/23/2025 - DURING TROUBLESHOOTING FOUND RH TEMP CONTROL VALVE STUCK IN FULL HEAT POSITION CAUSING RH AIR CONDITIIONING SYSTEM TO OVERHEAT AND SHUT DOWN.  REPLACED RH TEMP CONTROL VALVE PER AMM 21-61-1; TESTED PER 21-61-1 OPS CHECK GOOD.  PERFORMED CABIN PRESSURE CONTROL SYSTEMS PER AMM 21-32-0 3(A) OPS CHECK GOOD.

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