What happened
On the morning of 17 February 2021, a solo pilot operating a Bell 206B helicopter, registration ZS-HWZ, departed from a farm near Rhenosterhoekspruit for Wonderboom Aerodrome. While cruising at approximately 400 feet above ground level, the aircraft suffered an engine in-flight shut-down. The pilot immediately broadcast a distress message on the VHF frequency, alerting another pilot in the vicinity.
In an attempt to land safely, the pilot targeted a dirt road through dense bush. While attempting an autorotative approach, the main rotor blades struck a tree, causing the aircraft to pitch upward and yaw violently. The helicopter eventually came to rest on its skid gear in a nose-down position. While the pilot escaped without injury, the aircraft sustained substantial damage, including a severed tail boom and the separation of the main rotor assembly from the drive shaft.
The investigation
SACAA AIID investigators examined the wreckage and the engine components to determine the cause of the power loss. The investigation focused on the Rolls-Royce 250-C20J engine and the integrity of its pneumatic systems. Technical analysis of the engine's hardware revealed that the pneumatic Scroll-to-Pc Filter Tube Assembly had failed.
Investigators also reviewed maintenance records, including the most recent periodic inspection, and examined the installation procedures outlined in the engine's Operation and Maintenance Manual (OMM). The inquiry looked into the physical condition of the tube assembly and the presence of any environmental degradation that could have contributed to the component's failure.