# SDR DXTA2009010103454

- Type: Service difficulty report (as reported; unverified)
- Difficulty date: January 1, 2009
- Submitted: July 1, 2009
- Operation: Air carrier
- Aircraft: [N924QS](https://openairdocs.org/aircraft/N924QS), registered now
- Make and model: Cessna 750
- Registry model: [Cessna 750](https://openairdocs.org/model/cessna-750) (OpenAirDocs)
- Aircraft serial: 7500124
- Aircraft time: 7,925 hours, 4,811 cycles
- System (JASC): [2200 · Auto Flight System](https://openairdocs.org/jasc/2200)
- Part: Servo Drive
- Part number: 4006719903
- Part serial: 98030498
- Condition: Inoperative
- Location: Ailerons
- Part time: 4,400 cycles
- Stage of operation: DE
- How discovered: O
- Nature of condition: F, J
- Precautionary procedure: O
- FAA source: FAA Service Difficulty Reporting System (https://sdrs.faa.gov/)
- Page: https://openairdocs.org/sdr/DXTA2009010103454

## Discrepancy

DURING DESCENT, AUTOPILOT BEGAN TO ASCILLATE (ROLL).  DISENGAGED THE AUTOPILOT.  AFTER LEVELING AR 15,000, WE ATTEMPTED TO RE-ENGAGE THE AUTOPILOT, BUT WERE UNABLE.  CONCURRENTLY, THE "YD FAIL LOWER B" CAS MESSAGE WAS OBSERVED.  AUTOPILOT WOULD NOT ENGAGE.  ON THE GROUND, ATTEMPTED TO SWITCH FGCS, BUT WERE UNABLE.  "YD FAIL LOWER B" MESSAGE REMAINED ILLUMINATED.  REMOVED AND REPLACED AILERSON SERVO DRIVE ASSY 10. REMOVED AND INSTALLED "INSPECTED" SERVO DRIVE ASSY IAW MM SEC 22-10-01 REV 38. P/T DRIVE. F/TED OK. INSTALLED PANEL REMOVED FOR ACCESS.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.