Narrative:

I was doing the morning preflight on flight sjc to sna in 1/90, in advanced large transport. During the preflight I checked rudder trim travel left and right and thought I had it centered. When the captain came into the cockpit and started his duties, he asked why we had about 9-10 units of right rudder trim. I told him it was centered. We had maintenance look at the until. It was found that occasionally foreign matter between the bottom of the trim knob and the face of the control panel could hold the knob, over-driving the spring-centered knob to apply uncalled for rudder trim. This is a safety item and could be a problem if gone unnoticed.

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Original NASA ASRS Text

Title: CAPT OF ACR LGT QUESTIONS RUDDER TRIM POSITION DURING PREFLT CHECK. FO THINKS HE HAD ZEROED THE TRIM AFTER HIS TRIM CHECK AND SAYS THAT FOREIGN MATTER HAS BEEN FOUND TO HOLD THE TRIM KNOB OFF CENTER, THUS APPLYING AN UNWANTED SIGNAL TO THE TRIM MOTORS.

Narrative: I WAS DOING THE MORNING PREFLT ON FLT SJC TO SNA IN 1/90, IN ADVANCED LGT. DURING THE PREFLT I CHKED RUDDER TRIM TRAVEL LEFT AND RIGHT AND THOUGHT I HAD IT CENTERED. WHEN THE CAPT CAME INTO THE COCKPIT AND STARTED HIS DUTIES, HE ASKED WHY WE HAD ABOUT 9-10 UNITS OF RIGHT RUDDER TRIM. I TOLD HIM IT WAS CENTERED. WE HAD MAINT LOOK AT THE UNTIL. IT WAS FOUND THAT OCCASIONALLY FOREIGN MATTER BTWN THE BOTTOM OF THE TRIM KNOB AND THE FACE OF THE CONTROL PANEL COULD HOLD THE KNOB, OVER-DRIVING THE SPRING-CENTERED KNOB TO APPLY UNCALLED FOR RUDDER TRIM. THIS IS A SAFETY ITEM AND COULD BE A PROB IF GONE UNNOTICED.

Data retrieved from NASA's ASRS site as of July 2007 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.