What happened
On the morning of 9 December 2021, a Jabiru J430 aircraft, registration ZU-NDP, was conducting a private flight from Wings Park Aerodrome near East London to Virginia Aerodrome in KwaZulu-Natal. Approximately one hour into the flight, while flying near Port St Johns in the Eastern Cape, the engine suffered a sudden loss of power followed by a complete shutdown. The pilot identified a suitable landing site on the beach at Port St Johns and executed a forced landing. During the touchdown, the nose gear struck soft sand, causing the aircraft to come to a stop with minor damage to the airframe.
The investigation
Following the incident, the engine was removed for a detailed teardown inspection. Investigators discovered that the crankshaft had sheared. Laboratory analysis of the fractured crankshaft assembly revealed that the failure originated at the No. 1 conrod big end position through a fatigue failure mode. Microscopic examination showed extensive post-failure corrosion, suggesting exposure to high temperatures. Furthermore, the investigation identified significant wear on the main journal and crankcase bearings. A critical discrepancy was found regarding the No. 1 conrod big end bearing, which featured a different part number than the other bearings in the assembly. This specific bearing was identified as a non-manufacturer-approved part.
Findings
- The primary cause of the engine failure was a fractured crankshaft resulting from fatigue and heat-induced metal wear.
- The No. 1 conrod big end bearing was not a manufacturer-approved component.
- There was evidence of excessive wear and high-temperature exposure within the conrod assembly.
- The aircraft was fitted with larger tyres than specified by the manufacturer, including a modified nose gear strut assembly, for which no formal modification application was found in the regulatory database.
Safety action
- It is recommended that operators and Approved Maintenance Organisations (AMOs) verify that all engine and aircraft components are manufacturer-approved to prevent similar failures.
- It is recommended that the SACAA conduct audits of operators and AMOs to ensure compliance with approved parts and maintenance standards.