# SDR AALA202601056931

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: December 24, 2025
- Submitted: January 5, 2026
- Operation: Air carrier
- Aircraft: [N851NN](https://openairdocs.org/aircraft/N851NN), registered now
- Make and model: Boeing 737823
- Aircraft serial: 29556
- Aircraft time: 44,938 hours, 19,325 cycles
- System (JASC): [2211 · Autopilot Computer](https://openairdocs.org/jasc/2211)
- Part: Fmc
- Part number: 1762000101
- Part serial: 016629
- Condition: Abnormal
- Location: Zone 100
- Part time: 12,531 hours, 5,999 cycles
- Stage of operation: DE
- How discovered: O
- Nature of condition: O
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/AALA202601056931

## Discrepancy

AIRCRAFT WAS NOT GROUNDED: WHILE DESCENDING IN VNAV FROM FL280 TO FL 220 THE AIRCRAFT DID AN UNCOMMANDED LEVEL OFF AT FL 240 (THERE WERE NO RESTRICTIONS TO MAKE THE PLANE LEVEL OFF). LATER IN THE FLIGHT WHEN AT FL220 TRYING TO DESCEND TO 11000FT, PASSING THROUGH FL210, WHILE IN VNAV THE AIRCRAFT STARTED TO CLIMB BACK TOWARDS FL220 ON ITS OWN. **SUPPLEMENTAL REPORT FOR AALA202512296931 SUBMITTED 12/29/2025 BY TUL: MAINTENANCE REPLACED THE #3 FLIGHT MANAGEMENT COMPUTER (FMC) AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 34-61-02. ** (CLOSED)

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