Narrative:

While descending to 8000 ft passing through 8500 ft, aircraft sharply rolled left approximately 30 degrees then to the right. Engines at idle. Possible unscheduled control surface movement. Turned off yaw damper and autoplt after leveling wings and yaw checklist turned yaw damper back on per QRH. Hand flew aircraft to landing in cleveland. Callback conversation with reporter revealed the following information: this captain was flying a B737- 300 when he experienced uncommanded roll input to the left and the right. He attempted to correct by using both aileron and rudder, but the ailerons felt that they were not connected as there was no feeling of feedback. Also, the autoplt did not disconnect during the manual aileron inputs nor did it default to control wheel steering. After he disconnected the autoplt he regained full control of the aircraft. During his analysis and recovery the captain also shut off the yaw damper, but he restored that after he felt securely in control. After the event the captain was extensively interviewed by the company, the FAA and the manufacturer's representatives. He was told that there were numerous problems with the aircraft including a standby rudder hydraulic actuator shutoff valve that was frozen shut, the left leading edge devices that extended further than the right side, a protruding bolt on the left outboard slat would hold up its extension until the other devices were extended then this device would extend with a loud report. Additionally, a leak of some duration from the forward lavoratory had corroded and otherwise damaged the equipment in the forward electronics compartment bay. The various parties to the incident's investigation have agreed to the facts as stated by the flight crew except that the degree of bank according to the DFDR only indicated about 13 degrees of bank yet both pilots declared that the bank was at least 30 degrees in each direction.

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Original NASA ASRS Text

Title: LOSS OF ACFT CTL -- ACR EXPERIENCES UNCOMMANDED L AND R ROLLS WITH AUTOPLT ENGAGED. RECOVERED AFTER DISCONNECTING THE AUTOPLT.

Narrative: WHILE DSNDING TO 8000 FT PASSING THROUGH 8500 FT, ACFT SHARPLY ROLLED L APPROX 30 DEGS THEN TO THE R. ENGS AT IDLE. POSSIBLE UNSCHEDULED CTL SURFACE MOVEMENT. TURNED OFF YAW DAMPER AND AUTOPLT AFTER LEVELING WINGS AND YAW CHKLIST TURNED YAW DAMPER BACK ON PER QRH. HAND FLEW ACFT TO LNDG IN CLEVELAND. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS CAPT WAS FLYING A B737- 300 WHEN HE EXPERIENCED UNCOMMANDED ROLL INPUT TO THE L AND THE R. HE ATTEMPTED TO CORRECT BY USING BOTH AILERON AND RUDDER, BUT THE AILERONS FELT THAT THEY WERE NOT CONNECTED AS THERE WAS NO FEELING OF FEEDBACK. ALSO, THE AUTOPLT DID NOT DISCONNECT DURING THE MANUAL AILERON INPUTS NOR DID IT DEFAULT TO CTL WHEEL STEERING. AFTER HE DISCONNECTED THE AUTOPLT HE REGAINED FULL CTL OF THE ACFT. DURING HIS ANALYSIS AND RECOVERY THE CAPT ALSO SHUT OFF THE YAW DAMPER, BUT HE RESTORED THAT AFTER HE FELT SECURELY IN CTL. AFTER THE EVENT THE CAPT WAS EXTENSIVELY INTERVIEWED BY THE COMPANY, THE FAA AND THE MANUFACTURER'S REPRESENTATIVES. HE WAS TOLD THAT THERE WERE NUMEROUS PROBS WITH THE ACFT INCLUDING A STANDBY RUDDER HYD ACTUATOR SHUTOFF VALVE THAT WAS FROZEN SHUT, THE L LEADING EDGE DEVICES THAT EXTENDED FURTHER THAN THE R SIDE, A PROTRUDING BOLT ON THE L OUTBOARD SLAT WOULD HOLD UP ITS EXTENSION UNTIL THE OTHER DEVICES WERE EXTENDED THEN THIS DEVICE WOULD EXTEND WITH A LOUD RPT. ADDITIONALLY, A LEAK OF SOME DURATION FROM THE FORWARD LAVORATORY HAD CORRODED AND OTHERWISE DAMAGED THE EQUIP IN THE FORWARD ELECTRONICS COMPARTMENT BAY. THE VARIOUS PARTIES TO THE INCIDENT'S INVESTIGATION HAVE AGREED TO THE FACTS AS STATED BY THE FLC EXCEPT THAT THE DEGREE OF BANK ACCORDING TO THE DFDR ONLY INDICATED ABOUT 13 DEGS OF BANK YET BOTH PLTS DECLARED THAT THE BANK WAS AT LEAST 30 DEGS IN EACH DIRECTION.

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.