What happened
On January 27, 2001, a Robinson R-22 Beta, registration ZS-RBM, was engaged in a private flight originating from Durban. After a refueling stop in Harrismith, the pilot proceeded to a farm near Bethlehem. Following a visit to family, the pilot decided to remain at the location overnight due to deteriorating weather conditions, which included thunderstorm activity and the potential for hail.
To protect the aircraft from the weather, the pilot intended to move the helicopter into a nearby hangar. This required repositioning the aircraft closer to the hangar structure via a low hover. During this maneuver, the pilot encountered a decay in the main rotor RPM. In response, the pilot overreacted by dumping the collective, resulting in a hard landing. The impact caused the helicopter to bounce back into the air; upon the second touchdown, the left front skid assembly failed, causing the aircraft to roll over to the left. No injuries were reported.
The investigation
The investigation focused on the sequence of events during the low hover maneuver and the environmental conditions at the time of the accident. Investigators examined the aircraft's performance during the repositioning attempt and the pilot's reaction to the loss of rotor RPM. The investigation also looked into the pilot's familiarity with high-altitude operations, noting that the density altitude at the time was approximately 8,600 feet amsl.
Findings
- The primary cause of the accident was the pilot's overreaction to a sudden decay in main rotor RPM, which led to the hard landing and subsequent rollover.
- A significant contributing factor was the high density altitude of 8,600 feet amsl.
- The pilot's flying experience was primarily based in coastal regions, and they lacked sufficient familiarity with how high density altitude affects aircraft performance.