What happened
On 12 June 2018, a Mohawk aircraft, registration ZU-CRF, departed from Stilbaai Aerodrome in the Western Cape for a planned 30-minute scenic flight. The aircraft was operated as a private flight under Part 94 regulations. Shortly after rotating and climbing to approximately 300 feet above ground level, the engine experienced a total failure.
Faced with limited altitude and the presence of power lines in the immediate vicinity, the pilot was unable to restart the engine. To avoid the overhead wires, the pilot executed a forced landing, ditching the aircraft into the Stilbaai River. While the aircraft sustained substantial damage—including a broken propeller blade, airframe deformation, and water damage—there were no injuries to the pilot or the passenger.
The investigation
SACAA AIID investigators examined the engine and the flight circumstances. The investigation included a teardown of the Rotax 582 UL DCDI mod. 99 engine by an approved person. The inspection of the engine components revealed specific scarring on the piston and cylinder. The investigation also reviewed the pilot's credentials, noting a valid commercial pilot licence and medical certificate, as well as the aircraft's maintenance history, which showed the aircraft was within its inspection intervals.
Findings
- The primary cause of the engine failure was a cold seizure.
- This mechanical failure occurred because the internal engine components expanded at different rates during the initial period of operation, leading to physical restrictions between the piston and the cylinder.
- The pilot's decision to ditch in the river was influenced by the necessity to avoid power lines near the departure path.
- Meteorological conditions at the time of the accident were clear and had no bearing on the occurrence.