Narrative:

In cruise at 10;000 ft; #1 engine oil pressure gauge started moving back and forth from normal to caution range. While pulling out checklist; torque started to fluctuate. Within seconds; we heard loud banging sound and engine failed; followed by smoke in the cockpit. We put on our oxygen masks and goggles and started to run checklist. We declared an emergency; returned to ZZZ; and landed normally.

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Original NASA ASRS Text

Title: ATR72 flight crew suffered a left engine failure accompanied by smoke and audible indications of engine damage.

Narrative: In cruise at 10;000 FT; #1 engine oil pressure gauge started moving back and forth from normal to caution range. While pulling out checklist; torque started to fluctuate. Within seconds; we heard loud banging sound and engine failed; followed by smoke in the cockpit. We put on our oxygen masks and goggles and started to run checklist. We declared an emergency; returned to ZZZ; and landed normally.

Data retrieved from NASA's ASRS site as of April 2012 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.