What happened
On 21 April 2000, a Bushbaby microlight, registration ZU-BBW, was conducting a private flight from Cato Ridge Aerodrome toward Howick Aerodrome. While operating in the vicinity of the Albert Falls Dam in KwaZulu-Natal, the pilot experienced a sudden engine misfire. After notifying a nearby colleague in another aircraft of the emergency, the engine ceased functioning entirely.
In an attempt to avoid a collision, the pilot sought a suitable landing site, specifically targeting a road. During the descent, the pilot realized the glide ratio was insufficient to clear an orange orchard. The aircraft struck the tops of small orange trees, with the wings clipping a row of trees during the impact. While the Bushbaby sustained extensive damage to both wings, the pilot escaped the wreckage without injury, and no fire occurred.
The investigation
The investigation focused on the fuel system configuration and the sequence of the engine's failure. The aircraft's fuel system utilized two main tanks, one in each wing, which supply a header tank situated behind the pilot's seat. This header tank, which holds roughly 8 liters, is replenished from the main tanks via gravity feed. The engine receives fuel from this header tank through either gravity or an electrical pump. The investigation examined the state of the fuel valves and the consumption rate, noting that the engine consumes approximately 20 liters of fuel per hour at full power.
Findings
- The engine failure was caused by fuel mismanagement.
- Although the pilot departed with a full header tank, the fuel shut-off valves connecting the main tanks to the header tank remained closed.
- As the header tank was not being replenished, it eventually ran dry after approximately 30 minutes of flight, leading to the engine's total loss of power.