Tail boom severed during training autorotation in Kromvlei

Casualties unknown • In the Kromvlei training area, ZA

A Bell 206 B3 helicopter sustained significant damage after a hard landing caused by low rotor RPM during a training exercise.

What happened

On 6 April 2017, a Bell 206 B3 helicopter, registration ZS-HCZ, was conducting a Part 1lar1 training flight in the Kromvlei training area. The flight, operated by Henley Air, involved an instructor and a student pilot performing an autorotation exercise. During the final stage of the descent, the main rotor speed decreased significantly. This loss of RPM led to a hard touchdown, the force of which caused the main rotor to flex and subsequently sever the aircraft's tail boom. Despite the substantial damage to the airframe, there were no injuries to the two occupants.

The investigation

SACAA AIID investigators examined the sequence of events leading to the impact. The investigation focused on the flight dynamics during the autorotation maneuver, specifically the management of rotor revolutions per minute (RPM) and the execution of the flare. The inquiry reviewed the technical aspects of the landing, noting that the aircraft's main rotor blades sustained contact marks and the tail boom was structurally compromised by the rotor's movement during the hard landing.

Probable cause

The primary cause of the accident was the failure to maintain the minimum required rotor RPM during the autorotation, which resulted in a hard landing and the subsequent structural failure of the tail boom.

Frequently asked questions

What happened in the 2017-04-06 Bell 206 B3 Helicopter accident near In the Kromvlei training area, ZA?

A Bell 206 B3 helicopter sustained significant damage after a hard landing caused by low rotor RPM during a training exercise.

What aircraft was involved and where did it happen?

The accident on 2017-04-06 involved a Bell 206 B3 Helicopter, registration ZS-HCZ, at In the Kromvlei training area, ZA.

What was the probable cause of the accident?

The primary cause of the accident was the failure to maintain the minimum required rotor RPM during the autorotation, which resulted in a hard landing and the subsequent structural failure of the tail boom.

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