What happened
On the afternoon of 19 March 2025, a Piper Aerostar PA-60-600, registration ZS-NJD, departed Bethlehem Aerodrome (FABM) in the Free State province. The aircraft, carrying a pilot and five passengers, was on a private flight intended for Wonderboom Aerodrome in Gauteng.
Shortly after rotation at 90 knots, the aircraft failed to maintain its expected rate of climb. As the airspeed began to decay, the pilot realized the aircraft could not clear obstacles ahead. To avoid a more dangerous impact, the pilot executed a controlled forced landing with the gear retracted. The aircraft touched down approximately 500 meters beyond the end of Runway 11, skidding through a field and striking a tree before coming to a halt. While the aircraft sustained substantial damage to the fuselage, wings, and propellers, there were no injuries to the six occupants.
The investigation
SACAA AIID investigators examined the mechanical state of the aircraft's engines and the environmental conditions at the time of the accident. The investigation focused on why the aircraft lost thrust during the initial climb phase. Technical analysis of the propeller assembly revealed that the pitch-change cylinder on the right engine had loosened from its mounting. This separation caused an oil leak, leading to a drop in engine oil pressure, which subsequently triggered the propeller to auto-feather.
Findings
- The primary cause of the thrust loss was damaged threads on the propeller pitch-change cylinder, which likely occurred due to cross-threading during a maintenance installation.
- The loss of the right engine's thrust significantly degraded the aircraft's performance.
- High-density altitude (calculated at 7,195 feet) and the aircraft's weight near its maximum allowable limit further reduced the climb capability of the remaining operational engine.
- The pilot's decision to perform a belly landing was consistent with safety guidelines regarding engine failures during takeoff.