C152 instructor reported returning to departure airport due to rough running engine.

Attributes
ACN	1701470
Time
Date	201911
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna 152
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Pilot Flying Instructor
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Commercial Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 22 Flight Crew Total 1323 Flight Crew Type 502
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Clearance Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

Narrative:

Was climbing out of runway zzr and extending upwind as instructed by tower. Started having engine roughness and pulled carb heat on. Immediately lost power to 1200-1500 RPM at full power with firing noise out of exhaust and little smoke smell reported by student. Decided to turn around and informed power of imminent engine failure and intentions. Tower instructed to make right traffic. Made left turn while squawking 7700 and [requesting priority handling] and informed was coming back to the airport. Cleared to land runway xyr; held altitude and pitched for best glide until had runway made and descended for safe landing and taxi back to ZZZ. During run-up and flight on local practice area everything was normal.

Original NASA ASRS Text

Title: C152 Instructor reported returning to departure airport due to rough running engine.

Narrative: Was climbing out of Runway ZZR and extending upwind as instructed by Tower. Started having engine roughness and pulled carb heat on. Immediately lost power to 1200-1500 RPM at full power with firing noise out of exhaust and little smoke smell reported by student. Decided to turn around and informed power of imminent engine failure and intentions. Tower instructed to make right traffic. Made left turn while squawking 7700 and [Requesting Priority Handling] and informed was coming back to the airport. Cleared to land Runway XYR; held altitude and pitched for best glide until had runway made and descended for safe landing and taxi back to ZZZ. During run-up and flight on local practice area everything was normal.

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.