What happened
On 8 April 2001, a Tiger Moth aircraft, registration ZS-DHE, was involved in an incident during a private flight departing from Wonderboom Airport (FAWB). Following a standard refueling and pre-flight inspection, the pilot proceeded with the flight, which was intended to be a routine trip to the general flying area. After performing a complete power check and taxiing to the holding point for Runway 06, the aircraft began its takeoff roll. The aircraft successfully lifted off the runway at 55 mph and established a climb at 65 mph.
However, as the aircraft reached an altitude of approximately 200 feet above ground level and crossed Runway 11/29, the engine began running roughly, and the pilot experienced a partial loss of power. In an attempt to restore engine performance, the pilot initiated a right turn parallel to Runway 11/29. When the power loss could not be rectified, the pilot was forced to execute an emergency landing in a clearing located south of Runway 11/29. There were zero fatalities and two injuries resulting from the incident.
The investigation
SACAA AIID investigators examined the circumstances surrounding the engine malfunction and the flight profile leading up to the emergency landing. The investigation reviewed the pilot's pre-flight procedures, including the fuel checks and power assessments conducted prior to departure. The inquiry focused on the mechanical behavior of the engine during the climb phase and the subsequent loss of thrust.
Findings
While the investigation could not reach a definitive conclusion, the evidence pointed toward a specific fuel-related issue. The primary factor contributing to the engine's rough running and subsequent power loss was undetected water contamination in the fuel.