What happened
On May 8, 2015, a Cessna 172 S was conducting a training flight near Warsaw-Babice Airport (EPBC). Prior to the flight, a ground engine run test was performed, and the engine performance showed no issues.
Shortly after takeoff, at an altitude of approximately 150 feet, the pilot experienced engine vibrations. Despite these vibrations, the engine instruments showed no visible changes in operating parameters. The instructor notified Babice Radio of the situation and continued the flight, climbing to an altitude of 1,000 feet. After performing a 180-degree turn, the pilot coordinated with Air Traffic Control and was cleared to land. The landing was completed without further incident.
Following the flight, a second engine run test was conducted on the ground, which again showed no abnormalities. The aircraft was then handed over to the technical department, and the vibration incident was recorded in the aircraft's technical log.
The investigation
The investigation, conducted by the operator's internal commission, focused on identifying the source of the vibrations experienced during the climb. Technical personnel performed a thorough inspection of the engine and replaced the spark plugs. Following this maintenance, the engine operated normally, and no further vibrations were observed during subsequent flights.
Findings
- The investigation determined that the malfunctioning of one or more spark plugs was the probable cause of the engine vibrations experienced during the flight.