What happened
On 13 February 2017, a Piper PA-36-300 was conducting aerial crop spraying operations near the Settlers area in Limpopo Province. The flight departed from Roodekuil private strip under visual flight rules, intending to return to the same location. During the application process, the aircraft experienced a sudden engine failure.
In response to the loss of power, the pilot executed a forced landing in a field adjacent to the active spraying site. During the impact, the aircraft's main undercarriage collapsed, and the left wing made contact with a tree. While the aircraft sustained substantial damage, the pilot escaped the wreckage without any injuries.
The investigation
Following the accident, an Aircraft Maintenance Organisation performed a preliminary inspection of the engine. Maintenance personnel noted that the propeller could not be rotated by hand, indicating internal seizure. Further examination revealed that the engine crankcase had cracked from the inside out, specifically in the area of the number 7 and 8 cylinders.
A subsequent teardown inspection of the engine, conducted in April 2018, provided more technical detail regarding the mechanical failure. Investigators discovered that the nut on the No. 7 connecting rod big-end bearing was missing. The inspection showed evidence of fretting wear on the bolt threads and boltholes, suggesting that the nut had loosened over time. This separation caused the No. 7 connecting rod to detach from the crankshaft journal, which subsequently resulted in extensive damage to the camshaft.