What happened
On the afternoon of 4 March 2021, a Fokker E3 aircraft, registration ZU-FOK, was conducting a scheduled proving flight departing from The Coves Airfield in Gauteng Province. The flight was being operated under Visual Meteorological Conditions as part of a private flight program, with a specific authority to fly within a 100km radius of The Coves Estate.
Approximately 30 minutes into the flight, the pilot experienced a period of rough engine operation, which was immediately followed by a total engine stoppage. Faced with a loss of power, the pilot initiated an emergency forced landing into a nearby freshly ploughed field. While the landing attempt was successful in terms of reaching the ground, the uneven terrain of the field caused the aircraft to flip onto its back during the landing roll. The pilot escaped with minor injuries, but the aircraft suffered substantial damage.
The investigation
The investigation into the incident focused on the mechanical state of the aircraft and the circumstances surrounding the engine failure. The aircraft was powered by an HKS 700E engine, which is a non-type certified engine designed primarily for ultra-light and homebuilt aircraft.
Upon examination, investigators found no evidence of malfunctions in other aircraft systems, and the fuel levels were sufficient for the intended flight. The investigation could not determine a specific mechanical cause for the engine failure. Notably, the engine manufacturer's documentation includes a disclaimer stating that this specific engine type is capable of failing without prior warning during any stage of flight.
Findings
- The primary cause of the engine failure remains undetermined.
- The uneven surface of the ploughed field was the direct cause of the aircraft flipping during the landing roll.
- The HKS 700E engine is a non-type certified component that carries a known risk of sudden, unannounced failure.
Safety action
Following the incident, recommendations were made regarding the oversight of non-type certified engines. It was suggested that the Director of Civil Aviation review the use of engines that include disclaimers regarding sudden failure in non-type certified aircraft, as such disclaimers complicate accountability. Additionally, a recommendation was made to review how investigations are conducted for aircraft utilizing parts that carry manufacturer disclaimers regarding unannounced failure.