Tail Rotor Failure Leads to Helicopter Roll in Cape Town

Casualties unknown • Secondary School Groenvlei - Lansdowne – Cape Town, ZA

A Hughes 369HS helicopter engaged in a vehicle recovery operation experienced a catastrophic tail rotor failure, resulting in a hard landing and rollover in Lansdowne.

What happened

On 11 August 2000, a Hughes 369HS, registration ZS-HFE, was conducting a commercial Netstar vehicle recovery operation near Cape Town. The aircraft, carrying the pilot and two passengers, was orbiting a suspected vehicle at roughly 1,300 feet above ground level under clear weather conditions. During this maneuver, the pilot detected high-frequency vibrations through the directional control pedals.

In response to the vibration, the pilot initiated an autorotative descent. As the aircraft descended to approximately 150 feet, the tail rotor system detached from the airframe and made contact with the main rotor blades. The pilot struggled to maintain control as the aircraft developed a persistent tendency to dip to the right. While attempting to cushion the landing at 50 feet, the aircraft entered a right-hand spin. Upon touchdown, the aircraft completed a full 360-degree yaw and struck the ground at a 30-degree right roll attitude. The impact caused the right skid gear to collapse, resulting in the helicopter rolling onto its right side. There were no fatalities, though the pilot sustained a minor cut to the hand.

The investigation

Investigators examined the mechanical failure of the tail rotor assembly and the subsequent flight dynamics during the emergency descent. The inquiry focused on the structural integrity of the tail rotor components and the sequence of mechanical failures that led to the loss of directional stability. The investigation also reviewed the pilot's actions during the transition from a controlled descent to an unstable landing.

Findings

  • An unidentified event caused the loss of half of a tail rotor blade.
  • The resulting imbalance placed excessive load on the failed fork bore, causing one side of the fork bolt to become liberated.
  • The failure of the fork bolt, which bent and twisted until it broke, led to the pitch change links failing.
  • The detachment of the tail rotor rendered the aircraft progressively unstable.
  • The instability prevented a controlled autorotative landing, leading to a hard impact that collapsed the landing gear.

Probable cause

The accident was caused by the structural failure of the tail rotor assembly, initiated by the loss of part of a blade, which led to the failure of the fork bolt and the subsequent detachment of the tail rotor system.

Frequently asked questions

What happened in the 2000-08-11 Hughes 369HS accident near Secondary School Groenvlei - Lansdowne – Cape Town, ZA?

A Hughes 369HS helicopter engaged in a vehicle recovery operation experienced a catastrophic tail rotor failure, resulting in a hard landing and rollover in Lansdowne.

What aircraft was involved and where did it happen?

The accident on 2000-08-11 involved a Hughes 369HS, registration ZS-HFE, at Secondary School Groenvlei - Lansdowne – Cape Town, ZA.

What was the probable cause of the accident?

The accident was caused by the structural failure of the tail rotor assembly, initiated by the loss of part of a blade, which led to the failure of the fork bolt and the subsequent detachment of the tail rotor system.

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