What happened
On the morning of 1 March 2025, a Sling 2 aircraft, registration ZU-SIG, was conducting a private flight from Worcester Airfield in the Western Cape. The flight, which included a pilot and one passenger, proceeded normally through the general flying area before returning to the airfield for landing on Runway 1 and 5.
During the base leg of the approach, the pilot detected the smell of an electrical burn. As the aircraft turned toward the final approach at 65 knots and the pilot deployed 20 degrees of flaps, the engine ceased functioning and the instrument panel lost power. At approximately 300 feet above ground level, the pilot attempted an engine restart but was unable to restore power. Realizing the aircraft could not reach the runway, the pilot attempted a forced landing in a nearby field. However, the aircraft struck bush-type terrain roughly 400 metres short of the runway threshold. During the landing roll, the nose gear collapsed and the aircraft nosed over, causing substantial damage to the airframe, including the propeller, fuselage, and wings. Both occupants sustained minor injuries.
The investigation
SACAA AIID investigators examined the wreckage and the engine compartment to determine the source of the electrical failure. An inspection by an approved person revealed that a screw securing the electrical wires to the circuit breaker panel in the engine compartment had vibrated loose. This loose connection created a short circuit, causing the wire insulation to overheat and melt. Post-accident testing of the engine showed that the engine was capable of running normally once the loose screw was secured and the electrical issue was addressed.
Findings
- The engine stoppage was triggered by an electrical failure caused by a short circuit.
- The short circuit originated from a loose screw on the circuit breaker panel that had been loosened by vibration.
- The pilot's decision to execute a sharp turn during the engine failure likely increased the workload and contributed to the unsuccessful landing attempt.
- The aircraft's engine was found to be mechanically sound during subsequent ground testing.