What happened
On the morning of 24 March 2025, a Robinson R44 Raven II helicopter, registration ZT-RTF, was conducting a private flight from Howick Airfield to Ladysmith Aerodrome in KwaZulu-Natal. The flight was being operated under visual meteorological conditions for the purpose of refueling before continuing to Gauteng.
While approaching the airfield from the southeast, the pilot noticed the engine oil light flashing on the cockpit panel, accompanied by an abnormal engine noise and a low rotor RPM warning. The pilot immediately initiated an autorotation to perform a forced landing. During the descent, smoke was observed emanating from the right side of the engine cowls. The helicopter completed a hard landing on a grass area north of Runway 11/29. While the pilot escaped without injury, the aircraft sustained damage to the landing gear skids and the tail boom, with one main rotor blade severing part of the tail rotor assembly.
The investigation
SACAA AIID investigators examined the aircraft at its hangar in Gauteng. Although the engine oil level was found to be within limits, the engine could not be rotated manually. A subsequent teardown inspection of the engine revealed that the Number 3 piston was significantly damaged and was missing a piston pin plug.
Further analysis showed that the engine oil was heavily contaminated with metallic debris, including aluminium particles. This debris had clogged the oil pump suction filter screen and tubing. The investigation established that the presence of these particles led to a loss of lubrication, causing the failure of other internal components, such as the Number 5 cylinder connecting rod bearing.