Reporter discovers that rudder trim indicator is defective during his preflight inspection.

Attributes
ACN	129500
Time
Date	198911
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den
State Reference	CO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Dusk
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 : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp pilot : instrument
Experience	flight time last 90 days : 150 flight time total : 13700 flight time type : 2200
ASRS Report	129500
Person 2
Experience	flight time last 90 days : 150 flight time total : 13700 flight time type : 2200
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During cockpit setup I ran the electric rudder trim in both directions. The trim pointer remained at zero, then jumped 5 units. Ran trim several times observing rudder pedals moving. About half of the times the pointer would hang up then jump. Maintenance replaced indicator before departure. At no time did the flag appear. I recommend during cockpit set up to actually operate the rudder trim rather than just checking for zero trim.

Original NASA ASRS Text

Title: REPORTER DISCOVERS THAT RUDDER TRIM INDICATOR IS DEFECTIVE DURING HIS PREFLT INSPECTION.

Narrative: DURING COCKPIT SETUP I RAN THE ELECTRIC RUDDER TRIM IN BOTH DIRECTIONS. THE TRIM POINTER REMAINED AT ZERO, THEN JUMPED 5 UNITS. RAN TRIM SEVERAL TIMES OBSERVING RUDDER PEDALS MOVING. ABOUT HALF OF THE TIMES THE POINTER WOULD HANG UP THEN JUMP. MAINT REPLACED INDICATOR BEFORE DEP. AT NO TIME DID THE FLAG APPEAR. I RECOMMEND DURING COCKPIT SET UP TO ACTUALLY OPERATE THE RUDDER TRIM RATHER THAN JUST CHECKING FOR ZERO TRIM.

Data retrieved from NASA's ASRS site as of August 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.