Narrative:

I have no idea why the event occurred. Neither did the maintenance guy that preflighted our plane before we left the gate. On rotation the first officer brought to my attention that something was wrong with the trim on the aircraft. She said that she was having trouble controlling the aircraft. We cleaned up the aircraft and tried to get it under control. We climbed straight out runway heading to 5000 ft to troubleshoot the problem. We realized that there was something significantly wrong with the airplane and at that time declared an emergency with ATC. After running through the required emergency and normal checklists we were vectored around for the ILS. The aircraft was in such a state that it basically took both of us pulling back on the yoke to get the aircraft to flare for the landing. The rollout was uneventful and we taxied to the gate. Upon post flight we noticed that the inside spring tab on the right elevator was jammed in the full down position. We deplaned the aircraft and called dispatch to inform them what had just occurred. We realized that an event had occurred when we were unable to control the pitch of the aircraft on takeoff. We flew out straight ahead after takeoff to try and regain control of the aircraft. During the climb to our ATC assigned altitude we were troubleshooting to make sure that we had not missed anything as far as configuration problems or checklists. It is impossible for me to suggest anything that would help in avoiding this event in the future.supplemental information from acn 739819: we are not sure exactly what had caused the right spring tab to jam like it had done because we experienced no turbulence or gusts during our short taxi from the gate to the runway. Rolling down the runway for takeoff; I was the flying pilot and noticed there was something not right with the elevator or trim at rotation. I brought it to my captain's attention and we decided to climb straight out up to 5000 ft to troubleshoot the problem. Through trial and error we determined there was something significantly wrong with the aircraft and decided to come back around and land. We had to keep the aircraft below 200 KTS; 5 degree nose down pitch attitude; and a significant amount of forward force on the control wheel just to keep the aircraft straight and level. We declared an emergency and ran through our emergency procedures followed up by notifying the flight attendant; dispatch; and operations. The tower vectored us around for the ILS and we ran through our normal procedures to get set back up and come in to land. Coming in on final it required both the captain and I to flare the aircraft to the point where the control wheel was in the full aft position. We landed safely and taxied to the gate. As I was rolling down the runway I could tell on rotation that something didn't feel right with the controls so I questioned it and brought it to the captain's attention. We did not have any EICAS indications declaring that there was something wrong. When we determined something was significantly wrong with the aircraft we declared an emergency and followed normal emergency procedures and kept everyone informed. I feel that our flight crew had done everything possible during the preflight to try to avoid this situation.callback with reporter acn 739817 revealed the following information: the aircraft was preflighted by maintenance for the daily check just prior to the crew's arrival. The PF performed the exterior preflight with no discrepancies noted. At rotation; substantial force was required to keep the aircraft from pitching up excessively; with normal elevator trim being used to regain control. An emergency was declared and after troubleshooting; it was decided not to use elevator trim for the approach and landing unless absolutely necessary. The cause of the failure remains unknown.

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Original NASA ASRS Text

Title: EMB145 FLT CREW EXPERIENCED PITCH UP DURING TKOF. AFTER CLBING STRAIGHT OUT TO 5000 FT IT WAS DETERMINED THAT THE ACFT HAD A SIGNIFICANT TRIM PROB. THE FLT CREW DECLARED AN EMER AND RETURNED TO THE DEP ARPT.

Narrative: I HAVE NO IDEA WHY THE EVENT OCCURRED. NEITHER DID THE MAINT GUY THAT PREFLIGHTED OUR PLANE BEFORE WE LEFT THE GATE. ON ROTATION THE FO BROUGHT TO MY ATTENTION THAT SOMETHING WAS WRONG WITH THE TRIM ON THE ACFT. SHE SAID THAT SHE WAS HAVING TROUBLE CONTROLLING THE ACFT. WE CLEANED UP THE ACFT AND TRIED TO GET IT UNDER CONTROL. WE CLIMBED STRAIGHT OUT RWY HEADING TO 5000 FT TO TROUBLESHOOT THE PROBLEM. WE REALIZED THAT THERE WAS SOMETHING SIGNIFICANTLY WRONG WITH THE AIRPLANE AND AT THAT TIME DECLARED AN EMERGENCY WITH ATC. AFTER RUNNING THROUGH THE REQUIRED EMERGENCY AND NORMAL CHECKLISTS WE WERE VECTORED AROUND FOR THE ILS. THE ACFT WAS IN SUCH A STATE THAT IT BASICALLY TOOK BOTH OF US PULLING BACK ON THE YOKE TO GET THE ACFT TO FLARE FOR THE LANDING. THE ROLLOUT WAS UNEVENTFUL AND WE TAXIED TO THE GATE. UPON POST FLIGHT WE NOTICED THAT THE INSIDE SPRING TAB ON THE RIGHT ELEVATOR WAS JAMMED IN THE FULL DOWN POSITION. WE DEPLANED THE ACFT AND CALLED DISPATCH TO INFORM THEM WHAT HAD JUST OCCURRED. WE REALIZED THAT AN EVENT HAD OCCURRED WHEN WE WERE UNABLE TO CONTROL THE PITCH OF THE ACFT ON TAKEOFF. WE FLEW OUT STRAIGHT AHEAD AFTER TAKEOFF TO TRY AND REGAIN CONTROL OF THE ACFT. DURING THE CLIMB TO OUR ATC ASSIGNED ALTITUDE WE WERE TROUBLESHOOTING TO MAKE SURE THAT WE HAD NOT MISSED ANYTHING AS FAR AS CONFIG PROBLEMS OR CHECKLISTS. IT IS IMPOSSIBLE FOR ME TO SUGGEST ANYTHING THAT WOULD HELP IN AVOIDING THIS EVENT IN THE FUTURE.SUPPLEMENTAL INFO FROM ACN 739819: WE ARE NOT SURE EXACTLY WHAT HAD CAUSED THE RIGHT SPRING TAB TO JAM LIKE IT HAD DONE BECAUSE WE EXPERIENCED NO TURBULENCE OR GUSTS DURING OUR SHORT TAXI FROM THE GATE TO THE RUNWAY. ROLLING DOWN THE RUNWAY FOR TAKEOFF; I WAS THE FLYING PILOT AND NOTICED THERE WAS SOMETHING NOT RIGHT WITH THE ELEVATOR OR TRIM AT ROTATION. I BROUGHT IT TO MY CAPTAIN'S ATTENTION AND WE DECIDED TO CLIMB STRAIGHT OUT UP TO 5000 FT TO TROUBLESHOOT THE PROBLEM. THROUGH TRIAL AND ERROR WE DETERMINED THERE WAS SOMETHING SIGNIFICANTLY WRONG WITH THE AIRCRAFT AND DECIDED TO COME BACK AROUND AND LAND. WE HAD TO KEEP THE AIRCRAFT BELOW 200 KTS; 5 DEGREE NOSE DOWN PITCH ATTITUDE; AND A SIGNIFICANT AMOUNT OF FORWARD FORCE ON THE CONTROL WHEEL JUST TO KEEP THE AIRCRAFT STRAIGHT AND LEVEL. WE DECLARED AN EMERGENCY AND RAN THROUGH OUR EMERGENCY PROCEDURES FOLLOWED UP BY NOTIFYING THE FA; DISPATCH; AND OPS. THE TOWER VECTORED US AROUND FOR THE ILS AND WE RAN THROUGH OUR NORMAL PROCEDURES TO GET SET BACK UP AND COME IN TO LAND. COMING IN ON FINAL IT REQUIRED BOTH THE CAPTAIN AND I TO FLARE THE AIRCRAFT TO THE POINT WHERE THE CONTROL WHEEL WAS IN THE FULL AFT POSITION. WE LANDED SAFELY AND TAXIED TO THE GATE. AS I WAS ROLLING DOWN THE RUNWAY I COULD TELL ON ROTATION THAT SOMETHING DIDN'T FEEL RIGHT WITH THE CONTROLS SO I QUESTIONED IT AND BROUGHT IT TO THE CAPTAIN'S ATTENTION. WE DID NOT HAVE ANY EICAS INDICATIONS DECLARING THAT THERE WAS SOMETHING WRONG. WHEN WE DETERMINED SOMETHING WAS SIGNIFICANTLY WRONG WITH THE AIRCRAFT WE DECLARED AN EMERGENCY AND FOLLOWED NORMAL EMERGENCY PROCEDURES AND KEPT EVERYONE INFORMED. I FEEL THAT OUR FLIGHT CREW HAD DONE EVERYTHING POSSIBLE DURING THE PREFLIGHT TO TRY TO AVOID THIS SITUATION.CALLBACK WITH RPTR ACN 739817 REVEALED THE FOLLOWING INFO: THE ACFT WAS PREFLIGHTED BY MAINT FOR THE DAILY CHK JUST PRIOR TO THE CREW'S ARRIVAL. THE PF PERFORMED THE EXTERIOR PREFLT WITH NO DISCREPANCIES NOTED. AT ROTATION; SUBSTANTIAL FORCE WAS REQUIRED TO KEEP THE ACFT FROM PITCHING UP EXCESSIVELY; WITH NORMAL ELEVATOR TRIM BEING USED TO REGAIN CTL. AN EMER WAS DECLARED AND AFTER TROUBLESHOOTING; IT WAS DECIDED NOT TO USE ELEVATOR TRIM FOR THE APCH AND LNDG UNLESS ABSOLUTELY NECESSARY. THE CAUSE OF THE FAILURE REMAINS UNKNOWN.

Data retrieved from NASA's ASRS site as of January 2009 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.