Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 90; Flight Crew Total 1400; Flight Crew Type 970
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
The precautionary landing in question occurred on DATE. We prepared for takeoff and it seemed like another routine local flight with one of my students out of ZZZ. My student wanted to bring his son on the flight and I did not have a problem with it since we were in weight and balance. The density altitude was at 800 feet. When taking off Runway XXL; the student advanced the throttle to takeoff power; and I noted that the oil pressure; temperature; and RPM was in the normal operation range. The takeoff roll seemed a bit sluggish; but I thought it was because of the passenger's extra weight. At appropriate rotation speed; the student pitched the nose a little bit passed (Vy) attitude (closer to Vx) during the takeoff. I instructed him to pitch the nose down toward the proper (Vy) attitude; during the climb; the stall warning indicator activated. I crossed checked the airspeed and RPM. The rpm read 2100; which is below the normal engine operations; and the airspeed was reading 55 KIAS. Again; I instructed the student to keep pitching the nose down and noted that he was at a regular (Vy) attitude. I crossed check the airspeed and rpm; and we were indicating between 48-50 KIAS and 1800-1900 RPM. At that time; I took the flight controls; contacted ATC; and advised them that we needed to head back to the airport as soon as possible.While decreasing the angle of attack; the aircraft started to sink; and the stall warning horn continued with the RPM and airspeed not rising. I gave the plane an ample amount of time to recover from the unusual state we were in. I felt it was very uncommon for the aircraft to be performing like it was making a high-density altitude departure. ATC gave me the option to either try to make the left traffic pattern or head back to the airport. Because of the 15 degrees offset departure leg that is the practice at ZZZ; and the commercial buildings positioned southeast of Runway XXL were in my flight path; I believed the best course of action was to [advise ATC] [then] head immediately back towards the runway in the interest of safety. Once I [advised ATC]; I made a 30 degrees right bank and pitched the nose down to ensure I was not going to stall. I turned the aircraft around and landed on Runway XYL to ensure that I had plenty of distance to come to a safe stop. Once I landed the airplane; I exited on taxiway and told ATC why I [advised].
CE-172 Flight Instructor reported an uneventful air return landing due to a critical engine malfunction shortly after takeoff.