What happened
On 6 November 2000, a Robinson R22 helicopter, registration ZS-RHC, was conducting a private flight from Nelspruit to Sodwana. The flight proceeded without incident following a normal departure from Nelspruit. However, as the aircraft approached the mountain range situated between Nelspruit and Barberton, the pilot encountered a sudden loss of engine power. This loss of power prevented the aircraft from maintaining its altitude.
In response to the power loss, the pilot performed an autorotative landing. Due to the steep gradient of the terrain at the landing site, the helicopter rolled over upon impact. The incident occurred during daylight hours at an elevation of approximately 4,250 feet above mean sea level. There were two occupants on board, and both survived the event without injury.
The investigation
The investigation focused on the circumstances surrounding the loss of altitude and the subsequent landing on the mountain slope. Investigators examined the flight path, the meteorological conditions at the time, and the operational state of the aircraft. The investigation established that the weather conditions were fine at the time of the accident.
Findings
- The primary cause of the incident was a down draught located on the lee side of the mountain ridge near the accident site. This downdraft caused the helicopter to lose sufficient altitude that it could no longer clear the high ground.
- The steep slope of the terrain at the site of the emergency landing directly caused the aircraft to roll over during the landing maneuver.
- The investigation identified that the aircraft may have been overloaded, which served as a significant contributing factor to the inability to maintain flight following the loss of power.