What happened
On 6 August 2000, a Cessna 337, registered as ZS-IDO, was conducting a private local flight in the Bredasdorp region with one pilot and five passengers on board. While flying at 1,000 feet AMSL between Arniston and Cape Infanta, the pilot observed a decrease in oil pressure in the rear engine while passing the De Hoop Nature Reserve.
In response to the pressure drop, the pilot initiated a return to Bredasdorp. As the aircraft passed over Arniston, the pilot noted vibrations originating from the rear engine. To manage the situation, the pilot reduced power on the affected engine to roughly 2300 rpm and 20” manifold pressure. Shortly after this adjustment, two distinct loud bangs were heard approximately 20 seconds apart. The pilot proceeded to feather the rear engine and diverted the aircraft toward the Overberg Air Force base, where an emergency landing was successfully performed on runway 35. There were no injuries and no fatalities during the event.
The investigation
The investigation focused on the mechanical failure of the rear engine. Post-flight inspections of the engine revealed that the crankcase had sustained puncture holes. These holes were identified as being caused by the failure of internal components within the engine.
Findings
- The primary cause of the engine failure was an engine seizure.
- The seizure was triggered by the No. 2 main bearing being deprived of its necessary oil supply.
- This lack of lubrication led to the bearing seizing, which subsequently caused extensive damage to the engine components.