What happened
On 01 February 2011, a Piper PA28R-180 (registration ZU-BBG) was conducting a private local flight departing from Volksrust aerodrome in KwaZulu-Natal. While flying approximately 27nm north of Hluhluwe, the aircraft's engine suddenly ceased operation.
Faced with the loss of power and approaching mountainous terrain and trees, the pilot performed a forced landing on a flat, grass-covered hillside. To facilitate the landing, the pilot flew with the undercarriage retracted and full flaps extended. The aircraft came to rest within 50 metres of the initial touchdown point. While the pilot and passenger escaped no injuries, the aircraft sustained damage to the propeller blade tips, the lower engine cowling, and the right-hand flap.
The investigation
SACAA AIID investigators examined the engine components to determine the cause of the sudden power loss. The investigation focused on the engine, which had only 355.75 hours of operation since new. An inspection by an engine overhaul facility in Richards Bay provided critical technical details regarding the mechanical breakdown.
Findings
Technical analysis revealed that the engine failure was caused by a manufacturing defect involving the vacuum pump drive extension. Specifically, the oil port on this component had not been drilled at the engine factory. Because this port was missing, the shaft was unable to receive consistent lubrication and instead relied solely on incidental splash lubrication during flight.
This lack of proper lubrication eventually caused the shaft to seize. The resulting mechanical stress led to the failure of the dowel pin at the main drive gear on the crankshaft. This failure caused all engine-driven accessories to stop functioning, ultimately leading to the total engine failure. The investigation confirmed that the pilot was properly licensed and the aircraft had been maintained by an approved maintenance organisation.