What happened
On 15 June 2023, a DJI Matrice 300 RT Unmanned Aircraft System (UAS), registered as ZT-XHU, was conducting an aerial survey at the Anglo American Platinum Mogalakwena Mine in Limpopo Province. The mission, intended as a time study for a quarry pit blast block, was being operated under beyond visual line of sight (BVLOS) regulations.
During the flight, the secondary pilot-in-control took over operations while the primary pilot-in-command focused on ground control point plotting. After performing a pre-flight inspection and attaching the camera, the secondary pilot launched the aircraft. Shortly after takeoff, the remote pilot station displayed three error messages. The pilot then witnessed the drone enter an uncontrolled spiral, resulting in a crash. While the aircraft suffered substantial damage, there were no injuries to personnel on the ground.
The investigation
An investigation by the SACAA AIID examined the circumstances leading to the loss of control. The inquiry reviewed the pilot's credentials, noting a valid Remote Pilot Licence with appropriate BVLOS and multirotor ratings, as well as a valid medical certificate. The aircraft's documentation was also verified, including a valid Letter of Approval and a recent mandatory periodic inspection completed earlier that year.
Post-flight examination of the wreckage revealed that a propeller blade had separated from the aircraft during flight. The investigation focused on the sequence of events immediately preceding the detachment.
Findings
The investigation established that the primary cause of the accident was the detachment of a propeller blade in-flight, which created a propulsion imbalance and led to the loss of aircraft control. This failure was attributed to an improper pre-flight inspection, as the secondary pilot performed the checks in haste and failed to ensure the propeller was correctly secured before launch.