What happened
On the morning of 5 April 2007, a Robinson R22 Beta II helicopter, registration ZS-RMI, departed from Grand Central Aerodrome for a scheduled training session. The flight was being conducted by a commercial instructor and a student pilot, with the intention of returning to the aerodrome upon completion of the lesson.
Approximately thirty minutes into the flight, witnesses in the Morningside suburb of Johannesburg observed the aircraft flying at a high altitude with a slow forward speed. Suddenly, the helicopter's nose pitched downward, and the aircraft began a rapid descent. Observers noted that parts of the aircraft appeared to be detaching during the fall and that the main rotor blades were rotating at a significantly reduced speed. The helicopter ultimately struck a private residence at 100 East Hertford Road, crashing into a garden. The impact was so severe that the aircraft was destroyed, and both the instructor and the student pilot sustained fatal injuries.
The investigation
SACAA AIID investigators examined the wreckage and the engine to identify any mechanical failures that might have precipitated the descent. A reconstruction of the airframe was performed to check for structural integrity and potential in-flight breakage. The investigation also included a teardown of the Lycoming engine and an analysis of witness accounts.
Investigators found that the windshield had separated from the airframe prior to the final impact, and the fuel tank was ruptured upon hitting the ground. However, the examination of the engine and all flight control systems revealed no evidence of malfunction or pre-existing defects. All observed damage to the airframe and powerplant was consistent with the forces generated during the crash sequence. Furthermore, meteorological data confirmed that weather conditions were clear and suitable for visual flight, ruling out environmental factors as a cause.
Findings
- The aircraft was properly maintained, certified, and equipped according to all regulatory requirements.
- The pilot held a valid commercial license, and the student was on his second instructional flight.
- There was no evidence of any mechanical or engine failure prior to the loss of control.
- The aircraft struck the ground in a steep, nose-down attitude, indicating it was not under the pilot's control during the final moments of flight.