A B737-300 stabilizer trim motor actuator engaged in flight at FL350 and trimmed the stabilizer nose...

Attributes
ACN	850370
Time
Date	200909
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Elevator Trim System
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 219
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Inflight Event / Encounter Weather / Turbulence

Narrative:

While level at FL350 the aircraft trimming with the autopilot excessively. Since we were in vicinity of convective activity we contributed this to up and down drafts. The aircraft climbed to 35;300 ft before the autopilot disconnected along with a stab out of trim light. Appropriate checklist was run and autopilot was re-engaged. The excessive trimming continued and the autopilot was disengaged. We descended out of rvsm and requested a block altitude of 270 to 280 and we continued to our destination. We coordinated the decision to continue with dispatch and maintenance control. Upon landing; maintenance replaced a faulty autopilot stabilizer trim actuator.

Original NASA ASRS Text

Title: A B737-300 stabilizer trim motor actuator engaged in flight at FL350 and trimmed the stabilizer nose up until the autopilot disconnected and the STAB OUT OF TRIM light illuminated.

Narrative: While level at FL350 the aircraft trimming with the autopilot excessively. Since we were in vicinity of convective activity we contributed this to up and down drafts. The aircraft climbed to 35;300 FT before the autopilot disconnected along with a stab out of trim light. Appropriate checklist was run and autopilot was re-engaged. The excessive trimming continued and the autopilot was disengaged. We descended out of RVSM and requested a block altitude of 270 to 280 and we continued to our destination. We coordinated the decision to continue with Dispatch and Maintenance Control. Upon landing; Maintenance replaced a faulty autopilot stabilizer trim actuator.

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.

A B737-300 stabilizer trim motor actuator engaged in flight at FL350 and trimmed the stabilizer nose up until the autopilot disconnected and the stabilizer out of trim light illuminated.