What happened
On 17 April 2024, a Bushbaby 500 aircraft, registered ZU-EFA, departed Oudtshoorn Aerodrome (FAOH) for a private ferry flight to a destination near Plettenberg Bay. The flight was intended to move the aircraft for its scheduled 100-hour inspection. During the initial climb to 4,500 feet, the pilot observed higher-than-normal engine temperature indications. To manage the heat, the pilot reduced the rate of climb.
As the flight progressed into the cruise phase, the pilot noted that the cylinder head temperature (CHT) was not dropping as expected during descent. Approximately one hour into the flight, the engine power began to gradually decline. Unable to restore power, the pilot initiated an emergency descent and identified a grass field at Hillandale Hideaway as a suitable landing site. The aircraft performed a forced landing on the sloping terrain, resulting in a hard impact. The left main landing gear collapsed, and the propeller and left wing tip sustained damage. The pilot escaped the 0 fatalities incident without injury.
The investigation
An investigation by the SACAA AIID examined the mechanical state of the aircraft following the accident. While the engine was found to be capable of reaching full power during subsequent testing, inspectors identified a critical flaw in the engine cooling system's setup. It was discovered that the coolant radiator lacked sufficient airflow due to an improper installation by the original builder. Furthermore, investigators found that the coolant pipe fittings for the carburettor heat system were restricted, which directly contributed to the engine's inability to maintain power during the descent phase.
Findings
- The primary cause of the accident was an in-flight loss of engine power which necessitated the unsuccessful forced landing.
- A significant contributing factor was the improper installation of the engine cooling system, which prevented adequate thermal regulation.
- The aircraft sustained substantial damage to the landing gear, propeller, and wing tip.