# SDR ASAA2023092845358

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: September 28, 2023
- Submitted: September 29, 2023
- Operation: Air carrier
- Aircraft: [N564AS](https://openairdocs.org/aircraft/N564AS), registered now
- Make and model: Boeing 737890
- Aircraft serial: 35103
- Aircraft time: 62,078 hours, 18,495 cycles
- System (JASC): [3400 · Navigation System](https://openairdocs.org/jasc/3400)
- Part: Unknown
- Part number: UNKNOWN
- Condition: Unknown
- Location: Unknown
- Stage of operation: TX
- How discovered: V
- Nature of condition: J
- Precautionary procedure: K
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/ASAA2023092845358

## Discrepancy

BOTH FMCS DROPPED "OFF-LINE" MULTIPLE TIMES DURING PREFLIGHT. BOTH MCDUS ALSO WERE UNUSABLE. GROUNDED - YES. PERFORMED FMCS BITE PROCEDURE, FOUND FMC-L PGM FAULT ONE OCURRENCE AS PER FIM 34-61 TASK 801. PERFORMED FMCS RESET BY OPENING C/B'S A6 (FMCS CMPTR 1) AT P18-2 AND D16 (FMCS CMPTR 2) AT P6-1, WAITED FOR 30 SECONDS AND THEN CLOSED, AND VERIFIED FMC PROMPT SHOWS AT MCDU FOR SYSTEM #1 AND SYSTEM #2, OK TO CONTINUE AS PER FIM 34-61 TASK 807.

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