Jabiru J430 Engine Failure During Student Solo Circuit (ZU-FSF)

Incident Overview and Flight Details On 15 September 2025, a Jabiru J430 aircraft, registration ZU-FSF, was involved in a serious incident near Hartswater in South Africa's Northern Cape province. The flight was a solo circuit training exercise conducted by a student pilot under visual meteorological conditions. The aircraft departed from Herminie Farm and was intended to land at the same location. The incident occurred at 0620Z at GPS coordinates 27°47'48.58 S, 024°56'49.40 E, at an elevation of 4,228 feet. ## Sequence of Events The student pilot, a 42-year-old female holding a Student Pilot Licence, had completed four circuits with a flight instructor before commencing her solo training. The first solo circuit was uneventful. During the second circuit, the pilot initiated a go-around due to dissatisfaction with the approach. At approximately 1,000 feet above ground level, she reported hearing an unfamiliar noise from the engine, which subsequently failed. Despite unsuccessful restart attempts, the pilot executed a forced landing in a farm field. The aircraft sustained minor damage to the left main gear strut and left-wing tip, and the pilot was not injured. ## Engine Investigation and Findings A teardown inspection of the Jabiru 3300A engine (Serial Number 33A2485) revealed critical internal damage in cylinder Number 5. The piston was destroyed, with debris found in the oil sump and filter. The cylinder head, exhaust valve, and connecting rod were also damaged. Witness marks on the barrel indicated that a dislodged circlip caused the failure. One circlip was found bent, while the other was unrecognizable in the debris. The circlip groove on the piston was rough and smaller than standard, suggesting improper installation or wear. ## Probable Cause and Safety Context The probable cause was identified as the dislodging or failure of a circlip holding the gudgeon pin on the Number 5 piston, leading to uneven load distribution and piston failure. This resulted in engine failure and the subsequent forced landing. The aircraft had a valid Authority-to-Fly and Certificate of Release to Service, and the engine had not reached its time between overhaul limits. No contributing factors or safety actions were identified in the report.