What happened
On 22 July 2010, a Bushbaby 450 aircraft, registration ZU-ASL, departed from New Tempe Aerodrome for a local pleasure flight. The flight, which included the pilot and one passenger, was intended to be a short circuit returning to the same aerodrome. Approximately 45 minutes into the flight, the pilot experienced intense vibrations emanating from the engine.
In response to the mechanical instability, the pilot opted to perform an emergency landing on a flat, grassy area of a private farm located roughly 15 miles south of New Temable Aerodrome. During the landing attempt, the nosewheel struck a mound of soil and dug into the soft ground. This caused the aircraft to nose over and come to rest in an inverted position. While the aircraft suffered substantial damage to the wings, tail, and nose gear, there were no injuries to the occupants.
The investigation
SACAA AIID investigators examined the wreckage and the engine components at the owner's facility. The investigation focused on the source of the intense in-flight vibrations and the mechanics of the landing sequence. The examination of the Volkswagen 2.3 engine revealed that the mechanical disturbance was not due to external factors or pilot error in handling the aircraft, but rather a specific internal component failure.
Findings
- The aircraft was operating under valid authority and the pilot held a valid microlight license.
- Meteorological conditions at the time of the accident were clear with good visibility (CAVOK).
- The primary cause of the in-flight instability was a loosened stud from the flywheel, which caused the flywheel to vibrate and transmit heavy oscillations throughout the entire engine.
- The landing resulted in an aircraft nose-over because the nosewheel encountered a mound of soil and soft terrain during the forced landing sequence.