What happened
On the morning of 9 August 2024, a Jabiru SP aircraft, registration ZU-CNI, was completing a navigational flight returning to Grand Central Aerodrome (FAGC) in Gauteng. The flight, conducted under visual meteorological conditions, had previously visited Bela Bela and Loskop Dam.
As the pilot approached Runway 35, the landing was initially stable, with the main wheels making contact followed by the nose wheel. However, during the subsequent landing roll, the aircraft experienced a sudden yaw from left to right. The pilot noted a sensation of instability regarding the nose wheel, after which the left main landing gear strut collapsed. This caused the aircraft to veer off the left side of the runway. There were no injuries to the pilot, and the aircraft sustained minor damage.
The investigation
SACAA AIID investigators examined the aircraft at a maintenance facility to determine the cause of the gear collapse. The inspection focused on the main landing gear, which consists of composite beams bolted to the fuselage.
Investigators identified that the outer support bracket for the left main landing gear leaf spring strut had fractured. Analysis of the fracture surface revealed evidence of fatigue beach-marks and a clear zone exposed to the environment, suggesting the crack had been progressing for some time. Furthermore, mechanical smearing at the interface between the bracket and the leaf spring indicated that the failure was not a single-event overload, but rather a result of long-term stress. The investigation also noted that the level of wear suggested the bracket may have been subjected to high operational loads or improper bolt torque during previous maintenance.
Findings
- The primary cause of the accident was the failure of the left main landing gear outer support bracket due to fatigue.
- The fracture of this bracket caused the left leaf spring strut to fold backwards, leading to the loss of directional control during the landing roll.
- Evidence of mechanical wear and fatigue marks suggests the component had been failing progressively over time.
- The aircraft had undergone its last annual inspection in April 2024 and was within its valid maintenance period.