What happened
On September 29, 2013, a Cessna 152 departed from Radom-Piastów Airport (EPRP) for a flight intended to conduct pilot technique checks. The crew, consisting of a flight instructor and a student pilot, planned a route passing through Opoczno and Końskie. The flight initially proceeded without issue under favorable weather conditions.
At approximately 13:15, while flying at 1,800 feet near Końskie, the crew noticed vibrations originating from the engine. As the vibrations persisted and the engine power began to decrease, the pilots initiated an emergency landing procedure in a nearby field. During the final approach, at an altitude of approximately 100 to 120 meters, the engine failed completely and the propeller stopped rotating. The aircraft landed in a stubble field near Modliszewice, approximately 3 km northwest of Końskie. The aircraft sustained no damage during the landing, and the crew remained uninjured.
The investigation
Following the incident, the PKBWL investigation team examined the engine at the operator's facility. Upon removing the engine cowling, investigators identified damage to cylinder number 3. A detailed metallurgical analysis of the failed piston from cylinder number 3 was conducted.
Findings
Technical examinations revealed that the piston in cylinder number 3 had fractured at the plane of the wrist pin bore. The fracture pattern exhibited both low-cycle fatigue and sudden, ductile failure. The topography of the crack and the presence of fatigue striations indicated that a low-cycle fatigue crack had developed rapidly just prior to the final destruction of the component.
Investigators concluded that the fracture was caused by exceeding permissible operational stresses in the area of the wrist pin bore. This stress increase was most likely driven by high frictional resistance between the piston and the cylinder wall, potentially due to insufficient oil lubrication on the piston-cylinder interface. Evidence of scuffing was observed on the side surface of the piston. While the material of the piston was found to be free of manufacturing defects, the specific cause of the increased friction could not be determined. A review of maintenance records showed no irregularities, and the aircraft's oil level was confirmed to be above the minimum required limit following the flight.