An air carrier medium large transport crew found that its rudder trim seemed to have changed 10 unit...

Attributes
ACN	252755
Time
Date	199309
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dca
State Reference	DC
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
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 : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 24000 flight time type : 5000
ASRS Report	252755
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 8500
ASRS Report	253488
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I proceeded with my cockpit checks. Everything checked normal. I then left cockpit for a short while. When I returned and seated in my seat I rested my feet on the rudder pedals. I noticed my left foot was further in than the right. I reached up and turned on hydraulic pump thinking that jet blast or surface wind caused rudder displacement. This did not correct situation. About then, we were readying for pushback and engine start. After engine start and all hydraulic pumps turned on, rudder displacement did not change. It was then I rechked rudder trim and found it to be 10 degrees left. Cause of this is undetermined. Callback conversation with reporter revealed the following information: the reporting captain has no new notions as to what may have happened here, unless a window cleaner may have kicked the trim handle. The captain was not in the cockpit the whole time. He has not seen or heard of this happening again.

Original NASA ASRS Text

Title: AN ACR MLG CREW FOUND THAT ITS RUDDER TRIM SEEMED TO HAVE CHANGED 10 UNITS BY ITSELF.

Narrative: I PROCEEDED WITH MY COCKPIT CHKS. EVERYTHING CHKED NORMAL. I THEN LEFT COCKPIT FOR A SHORT WHILE. WHEN I RETURNED AND SEATED IN MY SEAT I RESTED MY FEET ON THE RUDDER PEDALS. I NOTICED MY L FOOT WAS FURTHER IN THAN THE R. I REACHED UP AND TURNED ON HYD PUMP THINKING THAT JET BLAST OR SURFACE WIND CAUSED RUDDER DISPLACEMENT. THIS DID NOT CORRECT SIT. ABOUT THEN, WE WERE READYING FOR PUSHBACK AND ENG START. AFTER ENG START AND ALL HYD PUMPS TURNED ON, RUDDER DISPLACEMENT DID NOT CHANGE. IT WAS THEN I RECHKED RUDDER TRIM AND FOUND IT TO BE 10 DEGS L. CAUSE OF THIS IS UNDETERMINED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTING CAPT HAS NO NEW NOTIONS AS TO WHAT MAY HAVE HAPPENED HERE, UNLESS A WINDOW CLEANER MAY HAVE KICKED THE TRIM HANDLE. THE CAPT WAS NOT IN THE COCKPIT THE WHOLE TIME. HE HAS NOT SEEN OR HEARD OF THIS HAPPENING AGAIN.

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.

An air carrier medium large transport crew found that its rudder trim seemed to have changed 10 units by itself.