C-172 flight instructor reported encountering a partial engine failure immediately after takeoff.

Attributes
ACN	1756422
Time
Date	202008
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Instructor Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Instrument Flight Crew Multiengine Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 133 Flight Crew Total 990 Flight Crew Type 715
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

On the initial climb after takeoff; I noticed we were flying 10 kts. Slower than normal and only maintaining level flight. Immediately after I noticed that; my student and I heard a popping sound and the airplane started to shake. I looked at the tachometer and noticed the RPM decreasing; so I pulled the power to idle; put in full flaps; and held a full slip to land back on the runway. I did this since we were experiencing a partial engine failure. My student and I were okay; and we were able to taxi the airplane back to the ramp.

Original NASA ASRS Text

Title: C-172 Flight Instructor reported encountering a partial engine failure immediately after takeoff.

Narrative: On the initial climb after takeoff; I noticed we were flying 10 kts. slower than normal and only maintaining level flight. Immediately after I noticed that; my student and I heard a popping sound and the airplane started to shake. I looked at the tachometer and noticed the RPM decreasing; so I pulled the power to idle; put in full flaps; and held a full slip to land back on the runway. I did this since we were experiencing a partial engine failure. My student and I were okay; and we were able to taxi the airplane back to the Ramp.

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.