AAIB investigation to DJI Matrice 200 V1, (UAS, registration n/a) 210919
Two occurrences of in-flight deployment of recovery parachute, near Raigmore Hospital, Inverness, 21 September 2019 and Montrose, Angus, 29 November 2019.
Summary:
The DJI Matrice 200 Unmanned Aircraft System (UAS) was being operated on an automated flight plan to conduct an aerial survey. On the fifth flight of the day, while the aircraft was at a height of 100 m, the ballistic parachute recovery system fitted to the aircraft activated. The aircraft descended under the parachute and was subsequently found on the roof of a nearby house.
Two months later, after having been repaired and fitted with a new parachute system, the aircraft experienced a second parachute deployment. On that occasion the aircraft was being manually flown in GPS mode at a height of 92 m over an area of open ground.
The first accident most likely occurred due to excessive vibration as a result of the parachute system not being securely attached to the airframe.
The investigation was unable to establish the cause of the second accident. There were several warnings in the recorded aircraft’s flight log, but analysis of this data did not provide any insight into why the flight was abruptly terminated. However, the parachute manufacturer considered that the second event involved a valid activation of the parachute system in response to a total aircraft power failure.
The investigation was limited by the availability of recorded flight data for the first accident and a lack of information from the UAS manufacturer. It was therefore unable to establish if there were any common factors between the two accidents, which involved the same aircraft but different parachute units. One Safety Recommendation is made regarding technical support to accident investigations by the UAS manufacturer.
In response to the first accident, the parachute manufacturer and the operator amended their respective procedures for securely attaching the parachute system to the aircraft.
The operator also identified that further emphasis on wind speed and direction was required prior to launch, to provide greater understanding of the drift potential in the case of a parachute deployment.
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