# SDR DL73S030431

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: May 6, 2003
- Submitted: May 27, 2003
- Operation: Air carrier
- Aircraft: N304DL
- Make and model: Boeing 737232
- Aircraft serial: 23076
- Aircraft time: 55,868 hours, 42,296 cycles
- System (JASC): [2120 · Air Distribution System](https://openairdocs.org/jasc/2120)
- Part: Valve
- Condition: Stuck
- Location: E&E Bay
- Stage of operation: CL
- How discovered: 9
- Nature of condition: J
- Precautionary procedure: A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/DL73S030431

## Discrepancy

IR: 20KFT CABIN ALTITUDE HORN WENT OFF.CBN ALT AT 11 KFT.  STARTED DESCENT SWITCHED TO STBY CBN WOULD NOT PRESS.  MANUAL MODE ALSO INOP.  REPLACED E & E COOLING EXHAUST VALVE. ALSO FOUND LEFT ENGINE 450 DEG THERMOSTAT SENSE LINE BACKED OFF.  TIGHTENED SAME,RAN ENGINES ACFT PRESSURIZED TO 5 PSID.

---
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.