# SDR AALA202509165144

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 11, 2025
- Submitted: September 16, 2025
- Operation: Air carrier
- Aircraft: [N921NN](https://openairdocs.org/aircraft/N921NN), registered now
- Make and model: Boeing 737823
- Aircraft serial: 33229
- Aircraft time: 36,444 hours, 16,018 cycles
- System (JASC): [2697 · Fire Protection System Wiring](https://openairdocs.org/jasc/2697)
- Part: Wire Harness
- Part number: 3250276030
- Condition: Faulty
- Location: Zone 400
- Stage of operation: CL
- How discovered: O
- Nature of condition: N
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/AALA202509165144

## Discrepancy

AIRCRAFT WAS GROUNDED: CLIMBING THROUGH AROUND FL230, WE RECEIVED 2 OVERHEAT DETECTION ALERTS FOLLOWED BY A FIRE BELL AND ENGINE 2 OVERHEAT. NO FIRE HANDLES ILLUMINATED. THE BELL LASTED UNDER 1 SECOND AND SELF EXTINGUISHED AND A FAULT LIGHT FOLLOWED.  ENGINE 2 PARAMETERS NORMAL. INSPECTED NUMBER 2 ENGINE INLET, EXHAUST AND EXTERIOR. NO SIGNS OF FIRE DAMAGE NOTED. FOUND ENGINE 2 LOOP-B FIRE DETECTION FAULTING. PERFORMED ENGINE FIRE DETECTION BITE CHECK, PER FIM 26-10-00-810-801. FOUND ENGINE 2 LOOP-B FAULT.  REPLACED M1759 DETECTOR (AALA202509121383), PER AMM 26-11-01. ALSO, REPLACED MW0326 HARNESS (AALA202509165144), PER AMM 26-11-02. OPERATIONAL CHECK GOOD.

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