What happened
On 21 October 2008, a Robinson R22 Beta II helicopter, registration ZS-RMJ, was conducting a training flight near Grand Central Aerodrome. The flight, involving a commercial instructor and a student pilot, was intended to practice autorotation and flaring maneuvers in the general flying area south of Allandale Road. After taking off from Runway 35 and climbing to 6,000 feet, the crew descended to approximately 6 feet above the ground to perform the maneuvers.
During the low-altitude exercise, the tail rotor struck an ant hill on the ground. This impact caused the helicopter to lose tail rotor effectiveness, resulting in a sharp left yaw. The aircraft subsequently struck the ground heavily on its skid. The force of the impact caused the tail rotor gearbox and the empennage to separate from the tail boom, while the main rotor blades and skids also sustained significant damage.
The investigation
SACAA AIID investigators examined the wreckage and the flight history of the aircraft. The investigation confirmed that the helicopter had been fully refueled before departure and was operating within its approved weight and balance limits. Maintenance records showed that the aircraft had undergone a Mandatory Periodic Inspection (MPI) only eight hours prior to the accident, performed by an accredited engineer.
Findings
- The primary cause of the accident was the tail rotor impacting an ant hill during low-level flight.
- A significant contributing factor was the failure of both the instructor and the student pilot to maintain adequate lookout for ground obstacles during the maneuver.
- There were no injuries to the two occupants.
- The aircraft sustained substantial structural damage, including the separation of the tail section components.