What happened
On 15 April 2002, a private pilot operating a Cessna P2/10N, registration ZS-KIW, departed from Lanseria for a local flight. During the flight, approximately 8nm northwest of the airfield, the pilot observed an unusually low fuel flow reading, despite the engine maintaining sufficient power. The pilot also noted a slight engine vibration, which persisted even after activating the low boost pump.
Deciding to return to the airfield, the pilot continued the flight with the engine performing well, though the fuel flow remained abnormal. However, while on final approach, the aircraft began to sink. The pilot attempted to increase power, but the engine failed to respond. Despite several emergency measures—including checking the magneto position, activating the boost pump, switching fuel tanks, and applying full throttle and a rich mixture—the engine remained unresponsive. The pilot issued a MAY-DAY call, notifying Lanseria ATC of an impending undershoot, before the aircraft crash-landed approximately 100m short of the airport boundary fence. The aircraft sustained extensive damage to the wings, propeller, and lower fuselage, though the pilot escaped without injury.
The investigation
SACAA AIID investigators examined the aircraft and the maintenance history of the engine. The investigation revealed that the engine had recently undergone extensive maintenance, including a major inspection and propeller balancing. During post-accident testing, it was discovered that debris had entered three of the six cylinders, causing the spark plug electrodes to close the gap and leading to engine failure.
Furthermore, the investigation identified contamination within the pipe leading to the fuel flow gauge, which had provided the pilot with a false indication of low fuel flow during the flight. The investigation also scrutinized the mechanical settings of the fuel system following a previous modification intended to prevent rich cuts.
Findings
- The primary cause of the engine failure was an incorrectly adjusted throttle linkage, which was set to 4 lbs at 15 inches of manifold pressure instead of the required 23 inches. This improper setting caused the engine to suffer a rich cut when the pilot retarded the throttle for landing.
- Contamination in the fuel flow gauge line resulted in a false low fuel flow reading.
- Debris in the cylinders caused spark plug malfunction.
- The pilot was properly rated and held a valid medical certificate at the time of the accident.