Narrative:

Flight had to return due to extreme torque fluctuations by engine #2 during climb out. As we were assigned to position and hold; aircraft on runway 27; the #2 engine; by its sound; could be heard having some type of small and quick fluctuations. The captain and I immediately looked at the engine gauges; and they indicated to be all in the green. We confer; and concluded that it was probably just a small glitch by the engine; and it was nothing out of the ordinary; and were still good to go. We proceeded with the before takeoff checklist; which was followed by the takeoff roll. After V1; vr; engine #2 had a drastic reduced in torque (at least 40%); and was followed by the engine trying to feather. The engine seemed to regain power and act normal for the next few seconds. At this point we requested vectors back to the airport. During the climb; the engine continued to fluctuate (-20% to 30% torque). At this point we declared an emergency. We kept the engine #2 on line; as it was still producing some kind of power; and we were already in the landing pattern. We performed the visual approach and landed with no further incident. Maintenance was called out; and all the passenger were deplaned.

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Original NASA ASRS Text

Title: AN ATR72 ON INITIAL CLB DECLARED AN EMER AND RETURNED TO THE DEP FIELD DUE TO R ENG FLUCTUATING TORQUE -20% TO +30%.

Narrative: FLT HAD TO RETURN DUE TO EXTREME TORQUE FLUCTUATIONS BY ENG #2 DURING CLBOUT. AS WE WERE ASSIGNED TO POSITION AND HOLD; ACFT ON RWY 27; THE #2 ENG; BY ITS SOUND; COULD BE HEARD HAVING SOME TYPE OF SMALL AND QUICK FLUCTUATIONS. THE CAPT AND I IMMEDIATELY LOOKED AT THE ENG GAUGES; AND THEY INDICATED TO BE ALL IN THE GREEN. WE CONFER; AND CONCLUDED THAT IT WAS PROBABLY JUST A SMALL GLITCH BY THE ENG; AND IT WAS NOTHING OUT OF THE ORDINARY; AND WERE STILL GOOD TO GO. WE PROCEEDED WITH THE BEFORE TKOF CHKLIST; WHICH WAS FOLLOWED BY THE TKOF ROLL. AFTER V1; VR; ENG #2 HAD A DRASTIC REDUCED IN TORQUE (AT LEAST 40%); AND WAS FOLLOWED BY THE ENG TRYING TO FEATHER. THE ENG SEEMED TO REGAIN PWR AND ACT NORMAL FOR THE NEXT FEW SECONDS. AT THIS POINT WE REQUESTED VECTORS BACK TO THE ARPT. DURING THE CLB; THE ENG CONTINUED TO FLUCTUATE (-20% TO 30% TORQUE). AT THIS POINT WE DECLARED AN EMER. WE KEPT THE ENG #2 ON LINE; AS IT WAS STILL PRODUCING SOME KIND OF PWR; AND WE WERE ALREADY IN THE LNDG PATTERN. WE PERFORMED THE VISUAL APCH AND LANDED WITH NO FURTHER INCIDENT. MAINT WAS CALLED OUT; AND ALL THE PAX WERE DEPLANED.

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.