What happened
On 11 December 2014, a Robinson R44 Raven II helicopter, registration ZS-RUP, departed from a private farm in the Bloemfontein district for a ferry flight to Klerksdorp. The flight, conducted under clear skies and visual meteorological conditions, began normally with the pilot performing standard power checks.
However, as the aircraft transitioned through approximately 20 feet of altitude, the pilot heard a loud bang from the rear of the aircraft. This was immediately followed by a significant decay in both engine and rotor RPM. In an attempt to manage the emergency, the pilot lowered the collective pitch and opened the throttle to regain rotor speed, but the loss of power persisted.
As the helicopter lost altitude, the pilot executed a forced landing straight ahead. During the landing sequence, the aircraft bounced upon initial contact with the ground. On the second contact, the skids caught in the grass. In an effort to prevent the helicopter from flipping forward, the pilot applied back pressure on the cyclic control, which caused the main rotor blades to strike the tail boom, effectively severing the tail section from the fuselage. There were no injuries to the pilot or the two passengers.
The investigation
SACAA AIID investigators examined the aircraft's mechanical components and the pilot's credentials. The investigation confirmed that the pilot held a valid commercial license and a current medical certificate. The aircraft's maintenance records showed that the last mandatory periodic inspection had been completed by an approved organization earlier that year, and the aircraft held a valid certificate of airworthiness.
Technical examinations focused on the engine and fuel systems. A teardown inspection of the Lycoming engine was conducted by an approved maintenance organization. Additionally, investigators tested the magnetos, spark plugs, and fuel injector nozzles for any signs of malfunction or blockage.
Findings
- The engine, magnetos, spark plugs, and fuel nozzles all showed no abnormalities that could explain the sudden power loss.
- The primary cause of the accident was an unsuccessful forced landing following an undetermined loss of engine power during the takeoff phase.
- The structural failure of the tail boom was a direct result of the main rotor blades making contact with the tail section during the landing maneuver.