Aircraft has full rudder deflection when engaging the autoplt.

Attributes
ACN	333194
Time
Date	199604
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mem
State Reference	TN
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : mem tower : huf
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 220 flight time total : 15000 flight time type : 13000
ASRS Report	333194
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

When engaging autoplt rudder kicked left and right several times then went to the right and stayed there. The autoplt rudder servo indicator was full scale to the right. Disengaging autoplt restored normal rudder. Callback conversation with reporter revealed the following information: shortly after takeoff he engaged the autoplt and the rudder fluctuated left and right a few times and then it went full right and stayed there. At this point he disengaged the autoplt. As the rudder moved left and right the wings remained level as the aircraft was flying in a xctl condition. When the aircraft rudder went to full deflection with the autoplt on, the pilot disengaged the autoplt. He did engage the autoplt one more time and the same type flight control maneuvers resumed. At that point he left the autoplt off for the remainder of the flight. At no time did the wings begin to roll into a bank or did any type of uncontrollable maneuver begin. Pilot disengaged the autoplt as it just felt uncomfortable flying in a xctled condition. The aircraft type was a DC9-30.

Original NASA ASRS Text

Title: ACFT HAS FULL RUDDER DEFLECTION WHEN ENGAGING THE AUTOPLT.

Narrative: WHEN ENGAGING AUTOPLT RUDDER KICKED L AND R SEVERAL TIMES THEN WENT TO THE R AND STAYED THERE. THE AUTOPLT RUDDER SERVO INDICATOR WAS FULL SCALE TO THE R. DISENGAGING AUTOPLT RESTORED NORMAL RUDDER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: SHORTLY AFTER TKOF HE ENGAGED THE AUTOPLT AND THE RUDDER FLUCTUATED L AND R A FEW TIMES AND THEN IT WENT FULL R AND STAYED THERE. AT THIS POINT HE DISENGAGED THE AUTOPLT. AS THE RUDDER MOVED L AND R THE WINGS REMAINED LEVEL AS THE ACFT WAS FLYING IN A XCTL CONDITION. WHEN THE ACFT RUDDER WENT TO FULL DEFLECTION WITH THE AUTOPLT ON, THE PLT DISENGAGED THE AUTOPLT. HE DID ENGAGE THE AUTOPLT ONE MORE TIME AND THE SAME TYPE FLT CTL MANEUVERS RESUMED. AT THAT POINT HE LEFT THE AUTOPLT OFF FOR THE REMAINDER OF THE FLT. AT NO TIME DID THE WINGS BEGIN TO ROLL INTO A BANK OR DID ANY TYPE OF UNCTLABLE MANEUVER BEGIN. PLT DISENGAGED THE AUTOPLT AS IT JUST FELT UNCOMFORTABLE FLYING IN A XCTLED CONDITION. THE ACFT TYPE WAS A DC9-30.

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.