What happened
On 13 October 2021, a Cessna 152 aircraft, registration ZS-PUR, was conducting a Part 1 lubricated training flight from Virginia Aerodrome to the Durban general flying area. The flight, occupied by a flight instructor and a student pilot, was intended to practice forced landing maneuvers.
During a simulated engine failure demonstration, the engine began to vibrate violently and experienced a partial loss of power while the aircraft was climbing through 1500 feet AGL. Although the instructor initially managed to stabilize the engine by adjusting the carburetor heat, the flight was aborted to return to Virginia Aerodrome. During the return leg, near the Galleria Mall, the instructor observed a significant drop in oil pressure. Shortly after this decline, the engine ceased operation entirely. The instructor declared a diversion to the Old Durban International Aerodrome and successfully executed a forced landing. There were no injuries to the occupants and the aircraft sustained minor damage.
The investigation
The investigation focused on the mechanical state of the engine and recent maintenance history. The aircraft had recently undergone a 100-hour mandatory periodic inspection on 5 October 2021, having flown only 18.8 hours since that service. Review of the flight records showed no prior reports of oil pressure or quantity issues.
Technical analysis by the maintenance organization revealed that a damaged crankshaft seal had caused an oil leak. This leakage led to the subsequent drop in oil pressure and the eventual seizure of the engine.
Findings
- The primary cause of the engine stoppage was an oil leak originating from a compromised crankshaft seal.
- The loss of oil pressure directly resulted in engine seizure during flight.
- The crankshaft seal, which had been installed during an engine overhaul in February 2018, failed during the period following the recent 100-hour inspection.