Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Instrument
Flight Crew Last 90 Days 180; Flight Crew Total 600; Flight Crew Type 580
Time Pressure
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft
While performing a checkout flight with a low time PPL I had the pilot perform an engine out drill by reducing the power to idle and informing the pilot the engine had failed. The drill was completed satisfactorily and I informed the pilot to recover at 1;000 feet MSL and climb to 2;000 to perform landings at [a nearby airport]. Shortly after the smooth application of full power the engine stumbled and began shaking. I took over controls of the aircraft and attempted to troubleshoot systems. All engine gauges indicated normal. The engine continued to run but with reduced power. I [notified ATC] and determined I was able to climb at approximately 100-200 fpm. I continued climbing at VY until I was within gliding range of ZZZ; proceeded inbound at 3;000 feet MSL; spiraled down once positioned above the runway; and landed without issue. The aircraft was able to taxi under its own power to transient parking. It was determined the aircraft had a stuck valve.
C172 instructor reported a rough running engine resulted from a stuck valve.