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A B737-300's autopilot stabilizer trim actuator failed at FL350 causing the aircraft to descend at 1;500 FPM. A TCAS RA was responded to by the captain who disconnected the autopilot and hand flew the aircraft the remainder of the flight.
| Attributes | |
| ACN | 892191 |
| Time | |
| Date | 201006 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Autoflight System |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Experience | Flight Crew Last 90 Days 169 Flight Crew Type 5000 |
| Person 2 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 244 Flight Crew Type 7000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural FAR Deviation - Procedural Published Material / Policy |
Narrative:
At FL350 we received a 'stab out of trim' light. We ran the checklist and continued. Several minutes later; the aircraft descended out of the assigned altitude with the autopilot engaged. As a result; we received a TCAS RA. The captain disengaged the autopilot and autothrottles; and climbed to satisfy the RA and get back to assigned altitude. ATC said there were no problems. The captain hand-flew the remainder of the flight. We landed uneventfully. Maintenance found a bad autopilot stab trim actuator and replaced it before our next flight.
Original NASA ASRS Text
Title: A B737-300's autopilot stabilizer trim actuator failed at FL350 causing the aircraft to descend at 1;500 FPM. A TCAS RA was responded to by the Captain who disconnected the autopilot and hand flew the aircraft the remainder of the flight.
Narrative: At FL350 we received a 'Stab out of Trim' light. We ran the checklist and continued. Several minutes later; the aircraft descended out of the assigned altitude with the autopilot engaged. As a result; we received a TCAS RA. The Captain disengaged the autopilot and autothrottles; and climbed to satisfy the RA and get back to assigned altitude. ATC said there were no problems. The Captain hand-flew the remainder of the flight. We landed uneventfully. Maintenance found a bad autopilot stab trim actuator and replaced it before our next flight.
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.