What happened
On 18 October 2024, a Dimona H36 Motor Glider, registration ZS-SKX, departed Potchefstroom Airfield for Beaufort West Airport. During the flight, the pilot noticed the fuel quantity indicator dropping rapidly, despite all other engine parameters appearing normal. Approximately 30 minutes later, the fuel gauge reached empty, causing the engine to surge and eventually stop entirely.
Following the engine failure, the pilot declared a Mayday. While attempting to reach Beaufort West, the pilot sought out thermals to maintain altitude; however, the available lift was insufficient. After approximately 18 minutes of gliding, the pilot identified a suitable landing site in an open field, roughly 12 nautical miles from the airport. The aircraft landed without damage, and both occupants exited the aircraft uninjured.
The investigation
An investigation into the cause of the fuel depletion was conducted by engineers at a maintenance organization. Upon inspection of the 82-litre aluminium fuel tank, investigators found evidence of minor leakage at the fuel gauge sender unit. More critically, a flexible fuel pipe located at the bottom of the tank was found to have disconnected from its fittings.
Technical analysis revealed that this pipe was not tightened according to the manufacturer's manual during the aircraft's last annual inspection. Because the pipe is positioned at the bottom of the tank, it is not visible during standard pre-flight inspections and is only accessible when internal panels are removed during heavy maintenance. The vibration experienced during flight eventually caused the improperly secured pipe to detach, leading to the rapid fuel loss.