What happened
On the evening of 1 November 2024, a Jabiru J170 aircraft, registration ZU-IBE, departed Rhino Park Aerodrome in Gauteng for a night training flight. The crew, consisting of a flight instructor and a pilot working toward a night rating, intended to fly via Witbank Aerodrome before landing at Wonderboom Aerodrome.
During the flight, the engine began running roughly. The pilot contacted air traffic control to declare a MAYDAY, requesting assistance to reach Runway 2 9 at Wonderboom. However, the aircraft was unable to reach the airfield. While attempting an emergency forced landing within the Carlsruhe Private Game Reserve, the aircraft struck high-tension powerlines. The impact triggered a massive fire fueled by the aircraft's fuel supply, resulting in two fatalities.
The investigation
An investigation by the SACAA AIID examined the wreckage and the engine components. Microscopic analysis of a cylinder from the engine revealed a circumferential fracture at the base flange. High-magnification inspection confirmed that the failure began with fatigue striations at two specific locations within the lipped section of the cylinder, near the crankcase. This fatigue eventually progressed into a final, rapid fracture.
Investigators also noted that the fracture occurred within the low-pressure zone of the cylinder. This suggests that while the crack may have been developing for some time, it likely only breached the cylinder during this final flight, as any significant oil seepage prior to the accident would have been detectable during routine inspections.
Findings
- The primary cause of the accident was the total loss of engine propulsion power caused by a fatigue crack on the No. 6 cylinder barrel.
- The aircraft struck high-tension powerlines during a forced landing on a moonless night.
- Potential contributing factors to the cylinder fatigue include incorrect cylinder fitment (improper torque application), which may have induced excessive tensile loads, or high levels of engine vibration.
Safety action
- It is recommended that the Original Equipment Manufacturer (OEM) revisit the engine assembly process to investigate the probabilities of improper fitment or other assembly-related stresses.