What happened
On 16 January 2010, a Helicycle helicopter, registration ZU-RBF, departed from a private landing zone at Swacina Park Agricultural Holdings for a visual flight rules trip to Rhino Park Aerodrome. Approximately six minutes into the flight, the aircraft began experiencing intense vibrations. The pilot attempted to stabilize the aircraft by reducing engine power and adjusting the collective pitch, which temporarily stopped the shaking. However, three minutes later, the vibrations returned.
In an attempt to manage the situation, the pilot initiated an autorotation toward an open field in the Mountain View suburb of Pretoria. During this maneuver, an attempt to increase power resulted in an engine flame-out. The pilot continued the autorotation without engine power, ultimately resulting in a hard landing. While the pilot escaped without injury, the helicopter sustained substantial damage, including a severed tail boom caused by the main rotor blades.
The investigation
SACAA AIID investigators examined the aircraft's maintenance history and flight preparations. The investigation revealed that the aircraft was being operated with an expired authority to fly. Furthermore, the investigation found that maintenance had been performed by unqualified individuals and that several critical maintenance actions were not documented in the aircraft's logbook.
Investigators also discovered an unauthorized modification intended to allow the center of gravity to be adjusted during flight, for which no installation records existed. Additionally, the pilot had personally attempted to adjust the trailing edges of the main rotor blades to correct a known stick shake, but these adjustments were performed incorrectly and were not recorded.