What happened
On May 24, 2015, a Cessna 152 Aerobat, registration OB-2066, was conducting a scheduled flight training mission at Pisco International Airport, Peru. The aircraft, operated by the flight school CIAC3 ESPAC, was carrying a flight instructor and a student pilot.
After completing several traffic patterns, the instructor noticed fluctuations in the engine oil pressure and notified air traffic control of the intent to return to the airport. During the return flight, the situation deteriorated as smoke appeared in the cockpit and oil pressure dropped critically. As the aircraft approached the runway, intense vibrations forced the instructor to execute an emergency landing. The aircraft landed successfully without causing major damage to the airframe, and the crew escaped without injuries. The airport's fire services responded immediately to the scene.
The investigation
The investigation focused on the engine components following the discovery of a separation between cylinder number two and the engine crankcase. Upon removing the engine cowling, investigators found that the cylinder had been forcibly detached from the crankcase due to a fracture.
Technical analysis of the engine revealed that cylinder number two showed evidence of a fracture around its base. Furthermore, the piston crown of cylinder number two exhibited deformation and burns caused by the critical leakage of high-temperature combustion gases and oil. The investigation also examined cylinders number three and four, finding evidence of overheating and wear, as well as carbon and lead deposits that indicated failures in oil circulation.