What happened
On the night of 8 March 2022, a survey flight conducted at the Glencore Coal Mine in Mpumalanga Province resulted in the destruction of a DJI Matrice 200 Series v2 drone, registration ZT-WPR. The operation was being performed under night-time visual meteorological conditions to investigate reports of illegal activity.
During the mission, the pilot maintained an altitude of approximately 65 feet above ground level. Roughly six minutes into the flight, the aircraft suddenly lost responsiveness and began to spiral out of control. The drone eventually disconnected from the controller and crashed, resulting in the destruction of the aircraft. There were no injuries reported during the incident.
The investigation
SACAA AIID examined the flight data and the condition of the aircraft following the crash. The investigation confirmed that the pilot held a valid Remote Pilot Licence with the necessary multirotor and visual line of sight endorsements. The operator also possessed the required letter of approval and operating certificate.
Pre-flight inspections had been completed, and the batteries and fail-safe settings were found to be in good working order. The aircraft had logged approximately 909 total flight hours and had undergone a maintenance inspection shortly before the accident. Flight data analysis revealed that during the mission, an Electronic Speed Controller (ESC) thrust warning was triggered.
Findings
Technical analysis of the flight logs identified that the right back motor failure was the primary driver of the accident. Specifically, the investigation established that the right back motor was spinning at 100% capacity, which caused the other propellers to fall out of sync. This mechanical instability led to compass interference caused by the motor spooling up, ultimately resulting in the loss of control and the subsequent crash.