Robinson R44 Crashes in Limpopo Due to Loss of Tail Rotor Effectiveness

Casualties unknown • Private farm Meletse in the Rooiberg district, ZA

A private helicopter flight ended in a ground impact in the Rooiberg district after a sudden wind gust triggered an uncommanded yaw.

What happened

On 1 December 2017, a Robinson R44 Raven II helicopter, registration ZS-RAT, was conducting a private flight from Wonderboom Aerodrome toward a farm in the Rooiberg district of Limpopo Province. The flight, which included the pilot and two passengers, was a routine trip to a destination the pilot had visited previously.

As the aircraft approached the helipad at Meletse farm from a northwesterly direction, it was flying at an altitude of approximately 50 feet. During the final stages of the approach, the aircraft encountered a strong gust of wind. This sudden change in wind conditions caused the helicopter to experience an uncommanded rapid yaw to the right. The pilot was unable to stabilize the aircraft's rotation, leading to an impact with the ground roughly 25 meters to the left of the intended approach path. While the helicopter suffered substantial damage, the three occupants escaped with only minor cuts and bruises.

The investigation

An investigation by the SACAA AIID established that the aircraft was operating within its weight and balance limits and possessed a valid certificate of airworthiness. The pilot held a valid private pilot license and medical certificate, though the investigation noted the pilot did not hold a night rating and the accident occurred during twilight, shortly after sunset.

Investigators examined the meteorological conditions, noting a southeast wind of 10 knots. Because the pilot was approaching the helipad from the northwest, the aircraft was subject to a tailwind component. The investigation also reviewed the pilot's experience, noting 147.9 total flying hours, with 21.5 hours on this specific type in the 90 days prior to the event.

Findings

  • The primary cause of the accident was the loss of tail rotor effectiveness (LTE).
  • The pilot failed to anticipate or correct for the prevailing downwind conditions during the approach.
  • The decision to approach the helipad from a northwesterly direction placed the aircraft in a wind azimuth (120° to 240°) highly susceptible to LTE.
  • The accident occurred during twilight conditions, following the 1645Z sunset.

Probable cause

The pilot's failure to account for and manage the tailwind conditions led to a loss of tail rotor effectiveness, resulting in an uncommanded rightward yaw and subsequent ground impact.

Frequently asked questions

What happened in the 2017-12-01 Robinson R44 Raven II accident near Private farm Meletse in the Rooiberg district, ZA?

A private helicopter flight ended in a ground impact in the Rooiberg district after a sudden wind gust triggered an uncommanded yaw.

What aircraft was involved and where did it happen?

The accident on 2017-12-01 involved a Robinson R44 Raven II, registration ZS-RAT, at Private farm Meletse in the Rooiberg district, ZA.

What was the probable cause of the accident?

The pilot's failure to account for and manage the tailwind conditions led to a loss of tail rotor effectiveness, resulting in an uncommanded rightward yaw and subsequent ground impact.

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