Narrative:

This flight was being conducted as a training flight. I the instructor initiated a shutdown of the right engine to: 1. Assess the trainees actions in identifying and securing the correct engine and 2. To demonstrate to the applicant the proper technique for restarting an engine at this altitude and that it may not even be possible to do a restart at this altitude. He demonstrated correct and proper technique. Upon his completion I moved the propeller control out of the feather position to prevent it from feathering and then moved the condition lever to the low idle position. I've demonstrated this exercise dozens of times successfully to numerous trainees with non eventful results. This time; when I moved the condition lever to the low idle position there was an almost immediate 'bang' from the engine and debris began exiting the exhaust stack. I immediately moved the condition lever to the idle cutoff position; feathered the propeller and we secured the engine according to the engine shutdown checklist. We declared an emergency and landed uneventfully.

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Original NASA ASRS Text

Title: A BE20 engine failed after being shutdown for training at FL270; then restarted at which time a bang was heard followed by debris exiting the engine.

Narrative: This flight was being conducted as a training flight. I the instructor initiated a shutdown of the right engine to: 1. Assess the trainees actions in identifying and securing the correct engine and 2. To demonstrate to the Applicant the proper technique for restarting an engine at this altitude and that it may not even be possible to do a restart at this altitude. He demonstrated correct and proper technique. Upon his completion I moved the propeller control out of the Feather Position to prevent it from feathering and then moved the Condition Lever to the LOW Idle position. I've demonstrated this exercise dozens of times successfully to numerous trainees with non eventful results. This time; when I moved the condition lever to the LOW Idle position there was an almost immediate 'bang' from the engine and debris began exiting the exhaust stack. I immediately moved the condition lever to the IDLE Cutoff position; feathered the propeller and we secured the engine according to the engine shutdown checklist. We declared an emergency and landed uneventfully.

Data retrieved from NASA's ASRS site as of July 2013 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.