Narrative:

Departing boston on the logan 9 departure we experienced runaway trim. Went through emergency procedures (captain and so) while I flew the aircraft. Aircraft did not respond well to both trim motors being disconnected. Declared emergency and flew to nearest suitable airport (syr). Dumped approximately 9000 pounds fuel en route. Landed at syr non-eventfully with emergency equipment standing by. I felt there was excellent crew coordination between the 3 cockpit crew members and the cabin flight attendants. Cockpit resource management training helpful in this incident. Callback conversation with reporter revealed the following information: this event was more a jammed full forward stabilizer than a runaway trim. The runaway trim procedure involves shutting off both electric trim motors. However, the cruise trim motor power was not interrupted when the circuit breaker was pulled and continued to drive the trim to the full forward position. When the manual trim was used to roll nose up it took a great deal of force and then, unless the pilot straight arm locked the trim from moving, it would run back to the full forward position. It took about 50 pounds of force to hold the control column to oppose the out of trim condition. By the 2 pilots distributing their efforts to lock the yoke back while they dumped the fuel and prepared the cabin for the possibility of losing control of the aircraft in the landing, they were able to wrestle the aircraft on the activities necessary to making a safe landing. Maintenance found some corroded terminals in the east and east compartment and went through with a major overhaul of the whole elevator system. An existing write up was a 'missing curtain' between the horizontal stabilizer and the elevator. The aircraft had sat overnight at boston in heavy rain before the flight the next morning with that curtain missing. The curtain is on the cdl equipment list. Supplemental information from acn 292356: the captain and first officer displayed amazing airmanship and saved the lives of all aboard.

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Original NASA ASRS Text

Title: THE STABILIZER WAS JAMMED FULL FORWARD, PROCS WERE ACCOMPLISHED, FUEL WAS DUMPED, EMER LNDG WAS MADE AT THE CLOSEST SUITABLE ARPT.

Narrative: DEPARTING BOSTON ON THE LOGAN 9 DEP WE EXPERIENCED RUNAWAY TRIM. WENT THROUGH EMER PROCS (CAPT AND SO) WHILE I FLEW THE ACFT. ACFT DID NOT RESPOND WELL TO BOTH TRIM MOTORS BEING DISCONNECTED. DECLARED EMER AND FLEW TO NEAREST SUITABLE ARPT (SYR). DUMPED APPROX 9000 LBS FUEL ENRTE. LANDED AT SYR NON-EVENTFULLY WITH EMER EQUIP STANDING BY. I FELT THERE WAS EXCELLENT CREW COORD BTWN THE 3 COCKPIT CREW MEMBERS AND THE CABIN FLT ATTENDANTS. COCKPIT RESOURCE MGMNT TRAINING HELPFUL IN THIS INCIDENT. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING INFO: THIS EVENT WAS MORE A JAMMED FULL FORWARD STABILIZER THAN A RUNAWAY TRIM. THE RUNAWAY TRIM PROC INVOLVES SHUTTING OFF BOTH ELECTRIC TRIM MOTORS. HOWEVER, THE CRUISE TRIM MOTOR PWR WAS NOT INTERRUPTED WHEN THE CIRCUIT BREAKER WAS PULLED AND CONTINUED TO DRIVE THE TRIM TO THE FULL FORWARD POS. WHEN THE MANUAL TRIM WAS USED TO ROLL NOSE UP IT TOOK A GREAT DEAL OF FORCE AND THEN, UNLESS THE PLT STRAIGHT ARM LOCKED THE TRIM FROM MOVING, IT WOULD RUN BACK TO THE FULL FORWARD POS. IT TOOK ABOUT 50 LBS OF FORCE TO HOLD THE CTL COLUMN TO OPPOSE THE OUT OF TRIM CONDITION. BY THE 2 PLTS DISTRIBUTING THEIR EFFORTS TO LOCK THE YOKE BACK WHILE THEY DUMPED THE FUEL AND PREPARED THE CABIN FOR THE POSSIBILITY OF LOSING CTL OF THE ACFT IN THE LNDG, THEY WERE ABLE TO WRESTLE THE ACFT ON THE ACTIVITIES NECESSARY TO MAKING A SAFE LNDG. MAINT FOUND SOME CORRODED TERMINALS IN THE E AND E COMPARTMENT AND WENT THROUGH WITH A MAJOR OVERHAUL OF THE WHOLE ELEVATOR SYS. AN EXISTING WRITE UP WAS A 'MISSING CURTAIN' BTWN THE HORIZ STABILIZER AND THE ELEVATOR. THE ACFT HAD SAT OVERNIGHT AT BOSTON IN HVY RAIN BEFORE THE FLT THE NEXT MORNING WITH THAT CURTAIN MISSING. THE CURTAIN IS ON THE CDL EQUIP LIST. SUPPLEMENTAL INFO FROM ACN 292356: THE CAPT AND FO DISPLAYED AMAZING AIRMANSHIP AND SAVED THE LIVES OF ALL ABOARD.

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.