Narrative:

During ATC assigned departure at approximately 900 ft and heading 050; the engine began to 'stumble'; operating at approximately 1300 RPM. This stumbling lasted approximately 5 seconds. At the beginning of the stumbling; this pilot began turning the aircraft back towards the field and lowering the nose. I had just checked in with departure when the stumbling began. I immediately advised ATC that I am returning to ZZZ reference a rough running engine. At the completion of that transmission; the engine began operating normally. The aircraft was placed back into a climb and I reduced the turn rate however I did continue to turn the a/C as if to position for a potential engine failure. Within several seconds; ATC advised to turn to heading 270 for the left downwind. I was asked by tower if my engine was operating normally. I advised it was currently normal. I was then cleared for landing on 9L while I heard tower diverting other landing traffic to other runways. Landing was performed normally and was cleared back to the ramp area. The a/C ran normally and all indications were normal following the initial engine stumbling. Pre-flight fuel checks revealed no contaminates or water. Post flight check of right tank revealed approximately two to three drops of water.

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Original NASA ASRS Text

Title: C172 instructor pilot reported suffering engine degradation right after takeoff for a brief period prompting the pilot to return to the departure airport.

Narrative: During ATC assigned departure at approximately 900 ft and heading 050; the engine began to 'stumble'; operating at approximately 1300 RPM. This stumbling lasted approximately 5 seconds. At the beginning of the stumbling; this pilot began turning the aircraft back towards the field and lowering the nose. I had just checked in with Departure when the stumbling began. I immediately advised ATC that I am returning to ZZZ reference a rough running engine. At the completion of that transmission; the engine began operating normally. The aircraft was placed back into a climb and I reduced the turn rate however I did continue to turn the A/C as if to position for a potential engine failure. Within several seconds; ATC advised to turn to heading 270 for the left downwind. I was asked by tower if my engine was operating normally. I advised it was currently normal. I was then cleared for landing on 9L while I heard tower diverting other landing traffic to other Runways. Landing was performed normally and was cleared back to the ramp area. The A/C ran normally and all indications were normal following the initial engine stumbling. Pre-flight fuel checks revealed no contaminates or water. Post flight check of right tank revealed approximately two to three drops of water.

Data retrieved from NASA's ASRS site 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.