History of Flight
On 3 August 2016, a Robinson R44 Raven II (registration ZS-RXW) departed Margate Airport, KwaZulu-Natal, at approximately 1150Z on a private flight. The pilot, accompanied by three passengers, intended to assist a fixed-wing pilot whose aircraft had a flat tyre and was parked on a private airstrip 4.2 nautical miles south-west of Mkambati ravine.
According to an eye-witness seated in a vehicle near a vulture deck construction area at the top of the ravine, the helicopter was observed approaching from the north-easterly direction at a low height of approximately 20 feet AGL. As it flew over the ravine, it suddenly pitched nose down. The main rotor blades then pitched up and severed the tail boom, after which the helicopter disappeared into the ravine. The helicopter impacted hard on the rocky surface and was destroyed. All four occupants sustained fatal injuries.
The investigation determined that at the time the helicopter began to fly over the ravine, it encountered strong turbulence resulting from strong head wind turbulence over the area. The helicopter was pushed down into the ravine, and the pilot may have attempted to take evasive action by putting excessive cyclic input, but was unsuccessful.
Probable Cause
The cause of the accident could be attributed to excessive control inputs by the pilot in an attempt to correct a low G-pushover condition, which resulted in the main rotor blades severing the tail boom.
Contributory Factors
1. Strong turbulence due to adverse weather condition prevailing in the area at the time of the flight.
Aircraft Information
The Robinson R44 Raven II (serial number 10881) was manufactured in 2005 and had a total airframe time of 3539.1 hours at the time of the accident. The engine was a Lycoming O-540 with 3539.1 hours since new and 1344.4 hours since overhaul. The helicopter was operated privately and had a valid Certificate of Airworthiness.
Weight and balance calculations indicated the helicopter exceeded the maximum allowable take-off weight of 2500 pounds by 114.05 pounds at take-off. The pilot did not perform mass and balance calculations for the flight.
Pilot Information
The pilot, a 48-year-old male, held a Private Pilot Licence valid and endorsed for the helicopter type. He had a total flying experience of 131.4 hours, with 75.3 hours on type. His license was issued on 28 January 2016, and his last flight folio entry was 18 July 2016. He had no previous accidents.