# SDR 2017FA0000564

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: November 9, 2017
- Submitted: November 9, 2017
- Operation: General aviation
- Aircraft: [N135SH](https://openairdocs.org/aircraft/N135SH), registered now
- Make and model: Lear 35A
- Registry model: [Lear 35A](https://openairdocs.org/model/gates-learjet-35a) (OpenAirDocs)
- Aircraft serial: 335
- Aircraft time: 10,416 hours, 9,005 cycles
- System (JASC): [2130 · Cabin Pressure Control System](https://openairdocs.org/jasc/2130)
- Part: Relief Valve
- Condition: Malfunctioned
- Location: Cabin Pressure
- Part time: 10,416 hours, 9,005 cycles
- Stage of operation: DE
- How discovered: O
- Nature of condition: J
- Precautionary procedure: B, A
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/2017FA0000564

## Discrepancy

AIRCRAFT LOST PRESSURIZATION DURING DECENT. CREW PERFORMED EMERGENCY LANDING. NO FURTHER INCIDENT ON LANDING. PERFORMED GROUND CHECKS OF PRESSURIZATION SYSTEM. COULD NOT DUPLICATE PROBLEM. FURTHER TROUBLESHOOTING REVILED INTERMITTENT FAULT IN DIFFERENTIAL RELIEF VALVE OPENING EARLY. REMOVED AND REPLACED DIFFERENTIAL RELIEF VALVE. PERFORMED FUNCTIONAL CHECKS OF PRESSURIZATION SYSTEM. ALL CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.

---
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.