Engine Oil Loss Leads to Forced Landing of Aerostar in Free State

Casualties unknown • Bethlehem Aerodrome, Free State, ZA

A Piper Aerostar experienced a loss of thrust following a mechanical failure during takeoff from Bethlehem Aerodrome, resulting in a belly landing with no injuries.

What happened

On the afternoon of 19 March 2025, a Piper PA-60-600 Aerostar, registration ZS-NJD, departed from Bethlehem Aerodrome in the Free State province. The flight, operated under private Part 91 regulations, was intended to be a return trip to Wonderboom Aerodrome.

Following a standard engine run-up and rotation at 90 knots, the aircraft failed to maintain its expected rate of climb. As the airspeed decayed and the aircraft began to lose altitude, the pilot retracted the landing gear and attempted to maneuver the aircraft away from a line of trees ahead. The aircraft subsequently performed a belly forced landing approximately 500 metres beyond Runway 11. The aircraft slid across the terrain, impacting several barrier fences and a small tree before coming to a halt. All six occupants, including the pilot and five passengers, disembodied from the aircraft without injury.

The investigation

SACAA AIID investigators examined the wreckage and the aircraft's maintenance history. The investigation focused on the mechanical state of the engines and propellers. Physical inspection of the aircraft revealed substantial damage to the underside of the fuselage, the wing leading edges, and both propellers.

Technicians discovered that the propeller pitch-changing mechanism housing cylinder on the right engine had detached from its mounting. This detachment caused a significant leak of engine oil. Further examination of the disassembled propeller assembly revealed that the threads on the ON switch were damaged. A metallurgical analysis has been commissioned to determine why the cylinder failed and detached from its position.

Findings

  • The primary cause of the loss of thrust was the detachment of the propeller pitch-changing mechanism housing cylinder on the number two engine.
  • This mechanical failure led to a significant loss of engine oil.
  • The resulting drop in engine oil pressure caused the variable pitch propeller to default to a feathered position, reducing the engine's effectiveness.
  • The aircraft sustained substantial damage to the belly, propellers, and wing leading edges during the forced landing.

Probable cause

The detachment of the propeller pitch-changing mechanism housing cylinder caused a loss of engine oil and a subsequent drop in oil pressure, forcing the propeller into a feathered position and resulting in a loss of thrust during takeoff.

Frequently asked questions

What happened in the 2025-03-19 Piper PA-60-600, Aerostar accident near Bethlehem Aerodrome, Free State, ZA?

A Piper Aerostar experienced a loss of thrust following a mechanical failure during takeoff from Bethlehem Aerodrome, resulting in a belly landing with no injuries.

What aircraft was involved and where did it happen?

The accident on 2025-03-19 involved a Piper PA-60-600, Aerostar, registration ZS-NJD, at Bethlehem Aerodrome, Free State, ZA.

What was the probable cause of the accident?

The detachment of the propeller pitch-changing mechanism housing cylinder caused a loss of engine oil and a subsequent drop in oil pressure, forcing the propeller into a feathered position and resulting in a loss of thrust during takeoff.

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