What happened
On the afternoon of 26 February 1999, a Piper PA18-150, registered as ZS-WSB, was conducting a test flight following recent maintenance work. The aircraft had recently undergone a cylinder replacement and repairs to a magneto defect. The flight was part of a series of tug launches operated by the Magalies Gliding Club.
During the 14th launch of the day, at approximately 1306 Z, the pilot experienced a sudden loss of engine power. Despite attempts to restart the engine, the power loss persisted. The pilot initiated an emergency plan to perform a forced landing in an open field. During the descent, the right-hand wing collided with a blue gum tree, causing the aircraft to strike the ground heavily. The impact resulted in the collapse of the undercarriage and caused the left-hand wing to contact the terrain. There were no fatalities and no injuries reported.
The investigation
Investigators examined the refueling process conducted earlier that morning. It was noted that 47.4 litres of fuel were transferred from a drum into the aircraft. The right-hand tank was filled to its full capacity of 68 litres, while the left-hand tank was filled until it reached approximately 35 litres.
Findings
- The primary cause of the engine failure was attributed to the pilot's failure to properly manage fuel levels, leaving approximately 35 litres of fuel in the left-hand tank.
- A contributing factor was a restriction in the right-hand fuel tank sight glass. The indicator ball within the sight glass was partially obstructed at the one-quarter fuel level due to a previous repair, which may have provided inaccurate fuel readings.