What happened
On May 23, 2018, at 10:05 UTC, a student pilot departed from Babice airport in a Cessna 152 for a cross-country flight to Nowe Miasto, intended to be flown at an altitude of 1,700 feet. After completing the cruise portion of the flight, the pilot began the approach for landing.
As the aircraft descended to 1,500 feet, the pilot activated the carburetor heat and reduced engine RPM to 1,500. At this point, the engine began to operate unevenly, with RPM fluctuations ranging between 1,100 and 1,500. In response, the pilot immediately applied full throttle and verified that the mixture was in the rich position; however, the engine continued to fluctuate between 1,200 and 2,000 RPM. After notifying the Flight Manager of the situation, the pilot was granted landing priority and instructed to execute an approach to runway 08 as an engine-out procedure. The landing was completed successfully without further incident.
The investigation
The investigation, conducted by the operator's internal commission, focused on the engine's performance during the descent. Following the landing, a detailed inspection of the engine was performed to identify the source of the power fluctuations.