# SDR 20010404SG001

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: March 2, 2001
- Submitted: March 22, 2001
- Operation: Air carrier
- Aircraft: N409US
- Make and model: Boeing 737401
- Aircraft serial: 23879
- System (JASC): [3620 · Pneumatic Indicating System](https://openairdocs.org/jasc/3620)
- Part: Thermostat
- Part number: 1296942
- Condition: Leaking
- Location: Nr 1 Engine
- 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/20010404SG001

## Discrepancy

TPA - FLT 1648 - CLIMBING THROUGH 8,000 FEET OUT TPA, EN ROUTE TO PIT, CREW ADVISED THAT THE NR 1 ENGINE OVERHEAT LIGHT ILLUMINATED.  POWER WAS REDUCED ON THE NR 1 ENGINE AND THE LIGHT EXTINGUISHED.  FLIGHT RETURNED TO FIELD AT TPA AND LANDED WITHOUT FURTHER INCIDENT.  NO EMERGENCY WAS DECLARED.  MAINTENANCE FOUND THE NR 1 ENGINE PRECOOLER CONTROL VALVE SENSOR AND 450 DEGREE THERMOSTAT O-RING BLOWN OUT.  REMOVED AND REPLACED THE SENSOR AND THE THERMOSTAT.  RAN NR 1 ENGINE TO POWER.  OPS CHECK AND LEAK CHECK GOOD.  REF USAASB01072.  (M)

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