What happened
On the evening of 1 January 2023, an ARACE, Sirin Multirotor UAV, registered as ZT-XNL, was conducting a night-time aerial surveillance mission near the Sibanye Platinum Hex River Helipad in Rustenburg. The flight was being operated under beyond visual line of sight (BVLOS) regulations.
After a successful takeoff and climb to 400 feet, the aircraft proceeded toward its programmed waypoints. However, upon reaching its initial surveillance position, the drone experienced a sudden loss of signal and disconnected from the controller. The aircraft failed to execute its return-to-launch sequence and crashed approximately 1.5 kilometres west of the launch site. The pilot was able to locate the wreckage using flight logs on Google Earth. The impact resulted in substantial damage to the fuselage, camera, and propeller blades, though no injuries were reported on the ground.
The investigation
An investigation into the incident examined the flight logs and maintenance history of the aircraft. The pilot was found to be properly licensed with the necessary BVLOS and multirotor ratings, and was medically fit for the operation. The operator held a valid operating certificate and the aircraft had undergone a recent inspection prior to the flight.
Analysis of the flight data via AIRDATA and Mission Planner revealed that the aircraft was climbing steadily and transitioning between flight modes when the failure occurred. The logs indicated that at 19:35:57 UTC, the aircraft experienced a sudden drop in both voltage and amperage, leading to a total loss of power. The pilot was unable to switch the aircraft to a return-to-home mode before the motors ceased operation.
Findings
The investigation concluded that the primary cause of the crash was a failure of the Universal Battery Eliminator Circuit (UBEC). This component, which regulates voltage for the flight electronics and cameras, failed during flight, causing the motors to stop turning and the aircraft to lose all rotary power.