What happened
On the morning of 25 October 2024, a private flight operating under Part 94 regulations encountered a critical mechanical issue. While en route from Springs Aerodrome (FASI) in Gauteng to Brits Aeroidrome (FABS) in the North West province, the pilot of the Jabiru SK, registration ZU-BSA, experienced significant engine vibrations approximately 25 minutes into the flight.
In response to the vibration, the pilot declared a Mayday via the TIBA frequency 124.8 MHz and initiated an emergency procedure. The pilot successfully executed a precautionary landing in an open field situated north of the N12 highway near Daveyton. During the landing maneuver, the aircraft's right main gear struck a rock, resulting in substantial damage to the wheel. The pilot disembarked from the aircraft without injury.
The investigation
Following the incident, an engine teardown was performed by an approved person to identify the source of the engine stoppage. The inspection of the engine (Serial No. 22A) revealed catastrophic internal damage. Specifically, the piston in cylinder number four had completely shattered, leading to a heavily deformed and twisted connecting rod. The cylinder head also showed significant pitting caused by the failing piston components.
Investigators noted that aluminum particles from the shattered piston were present in the oil sump. Additionally, a loose circlip, which is intended to secure the piston pin in place, was discovered among the debris in the oil sump. The investigation also confirmed that the engine had undergone a complete overhaul 786.8 hours prior, well within the 1000-hour overhaul interval, and the aircraft had received its annual inspection only 0.5 hours before the incident.