# SDR KCSA2020090214

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 2, 2020
- Submitted: September 8, 2020
- Operation: Air carrier
- Aircraft: [N713CK](https://openairdocs.org/aircraft/N713CK), registered now
- Make and model: Boeing 747-4B5F
- Registry model: [Boeing 747-4B5F](https://openairdocs.org/model/boeing-747-4b5f) (OpenAirDocs)
- Aircraft serial: 32808
- Aircraft time: 66,256 hours, 11,844 cycles
- System (JASC): [2612 · Fire Detection](https://openairdocs.org/jasc/2612)
- Part: Fire Detector
- Part number: 356412400
- Condition: Defective
- Location: Mlg Ww
- Stage of operation: CR
- 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/KCSA2020090214

## Discrepancy

FIRE WHEEL WELL. PER FIM 26-17 801. CHECKED WIRING FOR DAMAGE, CHAFFING, AND CORROSION.  NO DEFECTS NOTED. CHECKED FOR CONTINUITY AT PIN 10 OF RELAY TO GROUND, FOUND CONTINUITY.  REPLACED RELAY IAW BSWPM 20-81-22, NO HELP. THIS ITEM IS TRANSFERRED TO DMI 71300179 CAT "C" DUE DATE 12 SEPT 2020 (M).  PROCEDURES C/W IAW MEL 26-17-1B, PLACARDS INSTALLED.  REF DMI # 71300179 WHEEL WELL FIRE DETECTION SYSTEM INOP. PERFORMED RESISTANCE CHECK BETWEEN CONNECTOR DM694B & DM694A IAW B747-400 WDM 26-17-11.  FOUND SHORT TO GROUND ON M694B FIRE DETECTOR.  REMOVED AND REPLACED M694B FIRE DETECTOR IAW B747-400 AMM 26-17-02.  OPS CHECK GOOD IAW B747-400 AMM 26-17-00, NO DEFECTS NOTED, THIS DMI IS CLEARED.  ALL PLACARDS REMOVED.

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