What happened
On July 29, 2002, a Robinson R-22 Beta helicopter, registration ZS-RBZ, was conducting a game counting operation near a farm in the Alldays area. After refueling, the pilot and one passenger departed for a flight within the same area. The takeoff was initially smooth, and the aircraft began a slow climb. However, roughly ten seconds into the flight, a clutch amber caution light illuminated on the instrument panel.
In response to the warning, the pilot waited five seconds before pulling the clutch/start circuit breaker. To address the mechanical issue, the pilot identified a clear area of dry, desert-type terrain to perform an immediate landing. During the final approach to this landing zone, the aircraft experienced a sudden and rapid rate of descent. Despite the pilot applying maximum throttle and raising the collective to its maximum stop, the aircraft continued to lose altitude.
The helicopter struck the ground at a high forward speed, skidding across the terrain before striking an embankment. The impact caused the aircraft to roll onto its right side. The lower cockpit and cabin area suffered significant damage, with the instrument panel pressing against the pilot's chest. While the pilot escaped without major injury, the passenger sustained a broken leg and required hospitalization.
The investigation
SACAA AIID investigators examined the sequence of events leading to the impact. The investigation focused on the mechanical warning that prompted the emergency landing and the aerodynamic behavior of the aircraft during the descent. The pilot noted that the descent felt similar to encountering a severe downdraught in turbulent conditions, though he did not recall hearing the low rotor RPM aural warning or seeing the corresponding instrument activation.
Findings
- The primary cause of the accident was a rapid rate of descent during the approach to the landing site.
- The pilot's decision to land immediately was prompted by the activation of the clutch amber caution light.
- It is possible that the aircraft experienced a loss of translational lift shortly after takeoff, which necessitated the forced landing.
- The investigation considered that the pilot may have encountered severe dust, or a brown-out, during the final approach, which could have led to a loss of visual ground references and a subsequent hard landing.