Rudder trim position indicator jammed and or sticking as rudder trim position was changed.

Attributes
ACN	219429
Time
Date	199204
Day	Thu
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 180 flight time total : 7000 flight time type : 900
ASRS Report	219429
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During the ridder trim preflight check, we noticed the trim position arrow hung up. It remained at '0' when rudder trim was applied. It finally 'jumped' to 5 units and continued to jump. We discovered this could be flown in accordance with MEL. In light of rudder problem, I believe this MEL should be reviewed. Callback conversation with reporter revealed the following information. These aircraft have a history of runaway rudder trim motors. The problem reported here makes the matter worse, the trim could be running away and the cockpit indicator, an electrically driven instrument, would not indicate any motion of the rudder trim if it jammed.

Original NASA ASRS Text

Title: RUDDER TRIM POS INDICATOR JAMMED AND OR STICKING AS RUDDER TRIM POS WAS CHANGED.

Narrative: DURING THE RIDDER TRIM PREFLT CHK, WE NOTICED THE TRIM POS ARROW HUNG UP. IT REMAINED AT '0' WHEN RUDDER TRIM WAS APPLIED. IT FINALLY 'JUMPED' TO 5 UNITS AND CONTINUED TO JUMP. WE DISCOVERED THIS COULD BE FLOWN IN ACCORDANCE WITH MEL. IN LIGHT OF RUDDER PROBLEM, I BELIEVE THIS MEL SHOULD BE REVIEWED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. THESE ACFT HAVE A HISTORY OF RUNAWAY RUDDER TRIM MOTORS. THE PROBLEM RPTED HERE MAKES THE MATTER WORSE, THE TRIM COULD BE RUNNING AWAY AND THE COCKPIT INDICATOR, AN ELECTRICALLY DRIVEN INST, WOULD NOT INDICATE ANY MOTION OF THE RUDDER TRIM IF IT JAMMED.

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.