Narrative:

In cruise, autoplt on, the aircraft nosed over. The first officer and I both grabbed the yoke. The trim was inoperative and we had trouble getting autoplt to disengage. When it did the aircraft went nose up and through FL330 to FL335. We had no trim and advised ATC we needed to land and we made an unscheduled stop in south bend, in. Callback conversation with reporter revealed the following information: aircraft involved was an MD80 or an MD82. Crew had begun the flight sequence after major aircraft maintenance. The aircraft jack screw and all trim mechanisms had been replaced. The second leg flown was a las to cle flight. On departure, the aircraft encountered moderate to severe icing on climb out. All aircraft thermal anti-ice was used, which successfully handled the icing. After approximately 2 1/2 hours in cruise, the aircraft pitched nose down. The crew both grabbed the wheel to pull back. The captain also trimmed the aircraft nose up. This should have disconnected the autoplt. It did not. After the autoplt was overpowered, the resulting climb was stopped at about FL335. At this point the aircraft began an uncontrolled 30 degree bank right turn. The crew was unable to move the lateral trim. An emergency was declared and ATC was requested for vectors to the nearest suitable airport. After descending below the freezing level, all flight controls became normal. The crew was extensively debriefed by air carrier maintenance and engineering. All component items were replaced and the aircraft was given a flight test. All was found ok. On the next revenue flight, the aircraft had uncontrolled roll problems exactly as described previously. This aircraft remains grounded. Second conversaton with reporter revealed the following information: reporter stated in this subsequent callback that he was advised that this aircraft was given an examination by the manufature's engineering department. Including the FAA engineering and NTSB, to determine actual causal factors. The tail parts were all replaced again. Examination found that the moisture drain holes were all open, but that the aileron system had 2 discrepancies. The aileron trim control switch had a dead spot and the there was a notch in an aileron control gear which caused the aileron movement to lock up temporarily until manually overridden. The aircraft has now been back in service for two weeks with no reported problems. The investigators commented that it is difficult to positively determine the original cause of the problem after replacing all parts since each one individually checked ok, and therefore are not working together to find, with the exception of the parts of the aileron control system. The NTSB/FAA did review the flight recorder in their investigation.

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Original NASA ASRS Text

Title: MD80 HAD PITCH AND ROLL PROBS AT CRUISE, FL330.

Narrative: IN CRUISE, AUTOPLT ON, THE ACFT NOSED OVER. THE FO AND I BOTH GRABBED THE YOKE. THE TRIM WAS INOP AND WE HAD TROUBLE GETTING AUTOPLT TO DISENGAGE. WHEN IT DID THE ACFT WENT NOSE UP AND THROUGH FL330 TO FL335. WE HAD NO TRIM AND ADVISED ATC WE NEEDED TO LAND AND WE MADE AN UNSCHEDULED STOP IN SOUTH BEND, IN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: ACFT INVOLVED WAS AN MD80 OR AN MD82. CREW HAD BEGUN THE FLT SEQUENCE AFTER MAJOR ACFT MAINT. THE ACFT JACK SCREW AND ALL TRIM MECHANISMS HAD BEEN REPLACED. THE SECOND LEG FLOWN WAS A LAS TO CLE FLT. ON DEP, THE ACFT ENCOUNTERED MODERATE TO SEVERE ICING ON CLIMB OUT. ALL ACFT THERMAL ANTI-ICE WAS USED, WHICH SUCCESSFULLY HANDLED THE ICING. AFTER APPROX 2 1/2 HOURS IN CRUISE, THE ACFT PITCHED NOSE DOWN. THE CREW BOTH GRABBED THE WHEEL TO PULL BACK. THE CAPT ALSO TRIMMED THE ACFT NOSE UP. THIS SHOULD HAVE DISCONNECTED THE AUTOPLT. IT DID NOT. AFTER THE AUTOPLT WAS OVERPOWERED, THE RESULTING CLB WAS STOPPED AT ABOUT FL335. AT THIS POINT THE ACFT BEGAN AN UNCTLED 30 DEG BANK R TURN. THE CREW WAS UNABLE TO MOVE THE LATERAL TRIM. AN EMER WAS DECLARED AND ATC WAS REQUESTED FOR VECTORS TO THE NEAREST SUITABLE ARPT. AFTER DESCENDING BELOW THE FREEZING LEVEL, ALL FLT CTLS BECAME NORMAL. THE CREW WAS EXTENSIVELY DEBRIEFED BY ACR MAINT AND ENGINEERING. ALL COMPONENT ITEMS WERE REPLACED AND THE ACFT WAS GIVEN A FLT TEST. ALL WAS FOUND OK. ON THE NEXT REVENUE FLT, THE ACFT HAD UNCTLED ROLL PROBS EXACTLY AS DESCRIBED PREVIOUSLY. THIS ACFT REMAINS GROUNDED. SECOND CONVERSATON WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED IN THIS SUBSEQUENT CALLBACK THAT HE WAS ADVISED THAT THIS ACFT WAS GIVEN AN EXAMINATION BY THE MANUFATURE'S ENGINEERING DEPARTMENT. INCLUDING THE FAA ENGINEERING AND NTSB, TO DETERMINE ACTUAL CAUSAL FACTORS. THE TAIL PARTS WERE ALL REPLACED AGAIN. EXAMINATION FOUND THAT THE MOISTURE DRAIN HOLES WERE ALL OPEN, BUT THAT THE AILERON SYSTEM HAD 2 DISCREPANCIES. THE AILERON TRIM CONTROL SWITCH HAD A DEAD SPOT AND THE THERE WAS A NOTCH IN AN AILERON CONTROL GEAR WHICH CAUSED THE AILERON MOVEMENT TO LOCK UP TEMPORARILY UNTIL MANUALLY OVERRIDDEN. THE ACFT HAS NOW BEEN BACK IN SERVICE FOR TWO WEEKS WITH NO REPORTED PROBLEMS. THE INVESTIGATORS COMMENTED THAT IT IS DIFFICULT TO POSITIVELY DETERMINE THE ORIGINAL CAUSE OF THE PROBLEM AFTER REPLACING ALL PARTS SINCE EACH ONE INDIVIDUALLY CHECKED OK, AND THEREFORE ARE NOT WORKING TOGETHER TO FIND, WITH THE EXCEPTION OF THE PARTS OF THE AILERON CONTROL SYSTEM. THE NTSB/FAA DID REVIEW THE FLT RECORDER IN THEIR INVESTIGATION.

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.