Narrative:

This flight originated in minneapolis and was en route to aty (watertown, sd). Prior to the flight, the captain, myself (first officer) and an FAA avionics inspector who was a jumpseat rider preflted our mdt aircraft. We noticed no abnormalities during our preflight or our runway items flight control check and proceeded with a normal departure. Approximately 70 mi east of fsd, at cruise speed and at 10000 ft MSL, I began a climb to 12000 ft MSL due to a cloud layer and the possibility of turbulence. As the aircraft passed through 11000 ft MSL, I felt the elevator and elevator trim stick. While attempting to level the aircraft, by applying forward pressure, I felt the elevator pop free almost taking the controls out of my hands. This happened 3 or 4 times over a short period of time, maybe 15 to 20 seconds. I immediately notified the captain, who had already noticed we had a problem, and asked him to feel the controls which he did. The captain immediately felt the abnormality and flew the aircraft for most all the remainder of the flight. We decided to divert to fsd (sioux falls, sd) because it was closer and the WX (thunderstorms) was considerably better in that direction. At this time we went through our QRH (quick reference handbook) but it did not address this type of malfunction. We then declared an emergency and requested that crash fire rescue be standing by. The captain briefed myself, the flight attendant and our FAA jumpseat rider on evacuate/evacuation procedures. The captain and I then went through and completed the descent check while our flight attendant prepared the cabin for arrival. Prior to approach, we slowed the aircraft to approach speed to see how it would react at slower airspds. The captain then landed with partial flaps to minimize elevator and elevator trim travel. The landing was without incident. The captain, myself and our FAA jumpseat rider post-flight inspected the aircraft and didn't find anything out of the ordinary. Company authorized mechanics then examined the aircraft and determined the problem which they believed to be a screw that had lodged itself between the elevator and the elevator fairing. The screw is believed to have fallen out from right above the horizontal stabilizer, an area which isn't visible from ground level. While the mechanics were searching for the problem they found an additional problem that was unrelated to the first. The mechanics then fixed both discrepancies and signed them off per company procedure. The captain and I performed a test flight, which was satisfactory, then ferried the aircraft back to minneapolis without further incident.

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Original NASA ASRS Text

Title: ACR MDT ACFT ABNORMAL ELEVATOR CTL.

Narrative: THIS FLT ORIGINATED IN MINNEAPOLIS AND WAS ENRTE TO ATY (WATERTOWN, SD). PRIOR TO THE FLT, THE CAPT, MYSELF (FO) AND AN FAA AVIONICS INSPECTOR WHO WAS A JUMPSEAT RIDER PREFLTED OUR MDT ACFT. WE NOTICED NO ABNORMALITIES DURING OUR PREFLT OR OUR RWY ITEMS FLT CTL CHK AND PROCEEDED WITH A NORMAL DEP. APPROX 70 MI E OF FSD, AT CRUISE SPD AND AT 10000 FT MSL, I BEGAN A CLB TO 12000 FT MSL DUE TO A CLOUD LAYER AND THE POSSIBILITY OF TURB. AS THE ACFT PASSED THROUGH 11000 FT MSL, I FELT THE ELEVATOR AND ELEVATOR TRIM STICK. WHILE ATTEMPTING TO LEVEL THE ACFT, BY APPLYING FORWARD PRESSURE, I FELT THE ELEVATOR POP FREE ALMOST TAKING THE CTLS OUT OF MY HANDS. THIS HAPPENED 3 OR 4 TIMES OVER A SHORT PERIOD OF TIME, MAYBE 15 TO 20 SECONDS. I IMMEDIATELY NOTIFIED THE CAPT, WHO HAD ALREADY NOTICED WE HAD A PROBLEM, AND ASKED HIM TO FEEL THE CTLS WHICH HE DID. THE CAPT IMMEDIATELY FELT THE ABNORMALITY AND FLEW THE ACFT FOR MOST ALL THE REMAINDER OF THE FLT. WE DECIDED TO DIVERT TO FSD (SIOUX FALLS, SD) BECAUSE IT WAS CLOSER AND THE WX (TSTMS) WAS CONSIDERABLY BETTER IN THAT DIRECTION. AT THIS TIME WE WENT THROUGH OUR QRH (QUICK REF HANDBOOK) BUT IT DID NOT ADDRESS THIS TYPE OF MALFUNCTION. WE THEN DECLARED AN EMER AND REQUESTED THAT CRASH FIRE RESCUE BE STANDING BY. THE CAPT BRIEFED MYSELF, THE FLT ATTENDANT AND OUR FAA JUMPSEAT RIDER ON EVAC PROCS. THE CAPT AND I THEN WENT THROUGH AND COMPLETED THE DSCNT CHK WHILE OUR FLT ATTENDANT PREPARED THE CABIN FOR ARR. PRIOR TO APCH, WE SLOWED THE ACFT TO APCH SPD TO SEE HOW IT WOULD REACT AT SLOWER AIRSPDS. THE CAPT THEN LANDED WITH PARTIAL FLAPS TO MINIMIZE ELEVATOR AND ELEVATOR TRIM TRAVEL. THE LNDG WAS WITHOUT INCIDENT. THE CAPT, MYSELF AND OUR FAA JUMPSEAT RIDER POST-FLT INSPECTED THE ACFT AND DIDN'T FIND ANYTHING OUT OF THE ORDINARY. COMPANY AUTHORIZED MECHS THEN EXAMINED THE ACFT AND DETERMINED THE PROBLEM WHICH THEY BELIEVED TO BE A SCREW THAT HAD LODGED ITSELF BTWN THE ELEVATOR AND THE ELEVATOR FAIRING. THE SCREW IS BELIEVED TO HAVE FALLEN OUT FROM RIGHT ABOVE THE HORIZ STABILIZER, AN AREA WHICH ISN'T VISIBLE FROM GND LEVEL. WHILE THE MECHS WERE SEARCHING FOR THE PROBLEM THEY FOUND AN ADDITIONAL PROBLEM THAT WAS UNRELATED TO THE FIRST. THE MECHS THEN FIXED BOTH DISCREPANCIES AND SIGNED THEM OFF PER COMPANY PROC. THE CAPT AND I PERFORMED A TEST FLT, WHICH WAS SATISFACTORY, THEN FERRIED THE ACFT BACK TO MINNEAPOLIS WITHOUT FURTHER INCIDENT.

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.