What happened
On the morning of 5 April 2025, a Jabiru J430 with registration ZU-JHF departed from Heuningberg Farm in the Western Cape for a private flight to Morningstar Aerodrome. The flight, operated under Part 94 regulations, proceeded normally until approximately 14 minutes after takeoff. While flying south of Riebeek-Kasteel Town, the aircraft's engine began running roughly before failing completely.
Following the engine loss, the pilot declared a MAYDAY on the Cape Town International Aerodrome frequency. After identifying a suitable landing site, the pilot executed a forced landing in a ploughed wheat field. The aircraft touched down at 65 knots with full flaps, resulting in minor damage to the undercarriage due to the uneven terrain. No injuries were reported for the pilot or the passenger.
The investigation
An investigation by the SACAA AIID focused on the mechanical state of the engine and the operational parameters during flight. The aircraft was found to be airworthy and compliant with all maintenance requirements at the time of departure. Post-incident inspections of the engine revealed significant internal destruction; the engine could not be rotated by hand, and investigators discovered that the piston from the number 6 cylinder was missing from its barrel. Fragments of the piston, a bent connecting rod, and a failed inlet valve were recovered from the engine internals.
Findings
Technical analysis established that the engine had been subjected to extreme thermal stress. The Exhaust Gas Temperature (EGT) for the number 6 cylinder reached levels exceeding 800°C, which significantly surpassed the manufacturer's specified operating range of 600°C to 740°C. This overheating led to the structural failure of the piston, conrod, and inlet valve, ultimately causing the engine to cease operation.
Safety action
It is recommended that Jabiru Aircraft update the J430 Owner’s Manual to explicitly include the EGT limitations currently found only in the Engine Maintenance Manual, ensuring pilots are aware of these critical powerplant constraints.