What happened
On 22 December 2013, a pilot conducting a navigation and currency flight experienced a sudden loss of control while operating a Robinson R22 Beta, registration ZS-DLF. After completing a flight through Johannesburg, the pilot returned to the Grand Central Airport Helicopter General Flying Area to perform low-altitude maneuvers. While attempting to hover taxi at approximately 2 meters above the ground, the aircraft began descending at an unexpectedly high rate.
Despite the pilot's attempt to arrest the descent by pulling the collective, the aircraft continued to drop rapidly. The helicopter struck the ground in a nose-down attitude, causing the forward sections of the skids to break. The impact forces caused the aircraft to bounce back into the air before finally settling on its right side. The pilot, who was the sole occupant, sustained minor injuries to his face due to the aircraft being operated without doors.
The investigation
An investigation by the SACAA AIID examined the wreckage and the pilot's flight history. The inquiry confirmed that the pilot held a valid Commercial Pilot Licence and was medically fit at the time of the accident. Meteorological conditions were favorable, with good visibility and light winds.
Technical examination of the Robinson R2 and Beta components revealed that the damage to the tail boom, windscreen, and main rotor was a direct result of the impact forces. While the drive belts were found severed, investigators determined they were in acceptable condition prior to the crash; the breakage was caused by the clutch actuator extending beyond factory limits during the impact. No mechanical failures or airframe defects were identified as contributing to the initial loss of altitude.
Findings
- The primary cause of the accident was poor technique and airmanship, specifically the pilot's loss of control during a low-altitude landing attempt.
- The aircraft appeared to have entered a vortex ring state, a condition where the helicopter settles into its own downwash, resulting in a rapid, uncommanded descent that felt like a loss of power.
- The aircraft was being operated without doors, which is permitted under VFR regulations, but contributed to the pilot's facial injuries during the impact.