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A BE400 pitch/roll control knob apparently malfunctioned at FL450 causing the autopilot and yaw damper to disconnect. The aircraft began dutch rolling and descending with conflicting traffic in the vicinity.
| Attributes | |
| ACN | 833557 |
| Time | |
| Date | 200902 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | GA |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Beechjet 400 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Route In Use | Direct |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autopilot |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 41.1 Flight Crew Total 11100 Flight Crew Type 41.1 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Conflict Airborne Conflict Inflight Event / Encounter Loss Of Aircraft Control |
| Miss Distance | Horizontal 1000 |
Narrative:
We were flying at 43;000 ft when ATC asked if we would change altitude for crossing aircraft. We were just about to call ATC and ask for FL450 since we checked our weight and temperature for a higher altitude. Atc approved fl450 so we climbed quite easily to FL450 and after some time at 45;000 ft the autopilot went off which automatically disengages the yaw dampener. There is a limitation on beech 400 aircraft that if the yaw dampener fails the aircraft is restricted to FL280 and below. I grabbed the yoke and called for the autopilot to be reengaged and the other pilot tried to engage the autopilot to no avail. The aircraft was dutch-rolling the whole time and descending. I was informed that there was a crossing aircraft below us and asked for a turn to get out of the way of the crossing aircraft. Just below 44;000 ft I called for just the yaw dampener and the aircraft stopped yawing and I was able to hand fly the aircraft at 43;000 ft. We then tried to trouble shoot what caused the autopilot to fail we transferred the autopilot to the right side and the aircraft started to turn and both the auto dampener and autopilot failed we reinstalled the yaw dampener. And I looked at the pitch/roll control knob; which was centered; however; when I turned the outer ring roll control knob to the left and then back to center the problem stopped. The autopilot has not gone off since. I do believe that the problem has been solved.
Original NASA ASRS Text
Title: A BE400 pitch/roll control knob apparently malfunctioned at FL450 causing the autopilot and yaw damper to disconnect. The aircraft began dutch rolling and descending with conflicting traffic in the vicinity.
Narrative: We were flying at 43;000 FT when ATC asked if we would change altitude for crossing aircraft. We were just about to call ATC and ask for FL450 since we checked our weight and temperature for a higher altitude. Atc approved fl450 so we climbed quite easily to FL450 and after some time at 45;000 FT the autopilot went off which automatically disengages the yaw dampener. There is a limitation on Beech 400 aircraft that if the yaw dampener fails the aircraft is restricted to FL280 and below. I grabbed the yoke and called for the autopilot to be reengaged and the other pilot tried to engage the autopilot to no avail. The aircraft was dutch-rolling the whole time and descending. I was informed that there was a crossing aircraft below us and asked for a turn to get out of the way of the crossing aircraft. Just below 44;000 FT I called for just the yaw dampener and the aircraft stopped yawing and I was able to hand fly the aircraft at 43;000 FT. We then tried to trouble shoot what caused the autopilot to fail we transferred the autopilot to the right side and the aircraft started to turn and both the auto dampener and autopilot failed we reinstalled the yaw dampener. And I looked at the pitch/roll control knob; which was centered; however; when I turned the outer ring roll control knob to the left and then back to center the problem stopped. The autopilot has not gone off since. I do believe that the problem has been solved.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.