Propeller separation leads to forced landing of Gazelle aircraft

Casualties unknown • An open, rocky stretch of veld to the north of the farm "Sterkfontein", ZA

A private flight in the North West Province ended in an inverted landing after a propeller detached from the engine of a Gazelle aircraft.

What happened

On 24 February 2008, a Gazelle aircraft, registration ZS-WUP, was conducting a private flight from a farm in the North West Province toward Aeroden. Approximately one minute after departing from the farm "Sterkfontein," the aircraft reached an altitude of roughly 500 feet when the engine began to shudder. Shortly after this vibration, the propeller separated from the engine, forcing the pilot to execute an emergency landing.

The pilot identified a suitable area in an open, rocky stretch of veld and managed to maintain an airspeed of 65 mph until the aircraft was nearly 20 feet above the ground. However, during the touchdown, the nose wheel struck a rock and broke off. The impact caused the engine to separate from the airframe, and the aircraft eventually came to a halt in an inverted position. The pilot and a passenger both sustained minor injuries to their ankles.

The investigation

SACAA AIID investigators examined the wreckage and the failed propeller components. The investigation confirmed that the aircraft's Authority to Fly was valid and that the pilot was properly licensed. Metallurgical analysis of the propeller shaft was conducted to determine why the component detached during flight.

Testing of the propeller shaft revealed that the failure occurred at the base of the flange. The analysis showed clear evidence of a rotating-bending fatigue fracture that had been developing within the pulley shaft over an undetermined period. The examination also noted damage to the shaft in the clamp areas, suggesting it had been subjected to significant strain or rotational movement during operation.

Findings

  • The primary cause of the accident was an unsuccessful forced landing following the separation of the propeller from the engine.
  • The propeller detached because of a rotating-bending fatigue fracture that developed in the pulley shaft.
  • The aircraft sustained significant damage to the engine, the vertical stabilizer, both wings, and the front of the fuselage.
  • The propeller itself was found approximately 1 km from the crash site, where it had struck and damaged an electrical fence.
  • Weather conditions were calm with excellent visibility (CAVOK) and did not contribute to the event.

Probable cause

The propeller separated from the engine due to a fatigue fracture in the pulley shaft, which led to an unsuccessful forced landing where the aircraft struck rocks and overturned.

Frequently asked questions

What happened in the 2008-02-24 Gazelle accident near An open, rocky stretch of veld to the north of the farm "Sterkfontein", ZA?

A private flight in the North West Province ended in an inverted landing after a propeller detached from the engine of a Gazelle aircraft.

What aircraft was involved and where did it happen?

The accident on 2008-02-24 involved a Gazelle, registration ZS-WUP, at An open, rocky stretch of veld to the north of the farm "Sterkfontein", ZA.

What was the probable cause of the accident?

The propeller separated from the engine due to a fatigue fracture in the pulley shaft, which led to an unsuccessful forced landing where the aircraft struck rocks and overturned.

Loading the flight search…