What happened
On 18 February 2019, a DJI Matrice 210 was being operated during a test flight at a disused rail yard in Feltham, London. The flight was being conducted by the operator's Chief Pilot to evaluate the aircraft following recent minor repairs. The weather at the time consisted of light rain and low winds.
During the early stages of the flight, the unmanned aircraft performed normally. However, as the aircraft transitioned into a low hover toward the conclusion of the flight, a loud mechanical noise occurred. Immediately following this noise, the aircraft lost stability and tumbled to the ground, resulting in extensive damage.
The investigation
Following the accident, the aircraft was sent to the manufacturer for a technical assessment. The investigation examined the aircraft's recent history, noting that a few days prior to this incident, the drone had sustained light damage specifically affecting the area around motor No 1 and its electronic speed controller (ESC).
Technical analysis by the manufacturer determined that the electronic speed controller (ESC) for motor No 1 failed during the flight. While the investigation noted the previous damage to the motor area, it could not definitively conclude if that prior incident contributed to the failure.