Reporter notes design deficiency in rudder trim on advanced medium large transport.

Attributes
ACN	154233
Time
Date	199008
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zzz airport : xxx
State Reference	US
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	climbout : takeoff ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 30 flight time total : 4500 flight time type : 60
ASRS Report	154233
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

This letter references a weakness of safety warnings on the advanced medium large transport. The rudder trim switch (a knob) should have a mechanical guard around it, so the adjustment can't be changed inadvertently by a jumpseat rider resting a foot against the knob. Also, the trim switch range adjustment should be wired into the takeoff warning system in a method similar to the pitch trim range; ie, if the rudder trim setting until within +/- of center, the system sounds the takeoff warning system. Refer to the crash at lga, due to this defect.

Original NASA ASRS Text

Title: REPORTER NOTES DESIGN DEFICIENCY IN RUDDER TRIM ON ADVANCED MLG.

Narrative: THIS LETTER REFERENCES A WEAKNESS OF SAFETY WARNINGS ON THE ADVANCED MLG. THE RUDDER TRIM SWITCH (A KNOB) SHOULD HAVE A MECHANICAL GUARD AROUND IT, SO THE ADJUSTMENT CAN'T BE CHANGED INADVERTENTLY BY A JUMPSEAT RIDER RESTING A FOOT AGAINST THE KNOB. ALSO, THE TRIM SWITCH RANGE ADJUSTMENT SHOULD BE WIRED INTO THE TKOF WARNING SYS IN A METHOD SIMILAR TO THE PITCH TRIM RANGE; IE, IF THE RUDDER TRIM SETTING UNTIL WITHIN +/- OF CTR, THE SYS SOUNDS THE TKOF WARNING SYS. REFER TO THE CRASH AT LGA, DUE TO THIS DEFECT.

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.