ASN Wikibase Occurrence # 315433
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| Date: | Tuesday 17 August 2021 |
| Time: | 00:36 |
| Type: | DJI Matrice 300 |
| Owner/operator: | Gloucestershire Police |
| Registration: | unreg. |
| MSN: | 1ZNDHAL00CPC93 |
| Fatalities: | Fatalities: 0 / Occupants: 0 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Cam, Dursley, Gloucestershire -
 United Kingdom
|
| Phase: | Approach |
| Nature: | Survey |
| Departure airport: | Cam, Dursley, Gloucestershire |
| Cam, Dursley, Gloucestershire | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
AAIB investigation to DJI Matrice 300, (UAS registration n/a): UA became unresponsive as it returned to its landing site, Cam, Dursley, Gloucestershire, 17 August 2021.
The unmanned aircraft (UA) was completing an aerial search flight and whilst on approach to its landing site, it became unresponsive and dropped to the ground. Its motor carrier arms were damaged when the UA hit the ground. The nature of the damage suggests, although is not conclusive, that one of the arms was not correctly locked in place. In this condition it is possible the thrust from that rotor became variable rendering the UA unresponsive to control inputs.
=Examination of the UA=
In this design, the motor arms are hinged to enable them to be folded to allow the UA to fit in its transportation case. When the arms are extended during preparation for flight, they are each locked in place by a ‘twist to lock’ collar.
An examination of the UA by the operator found that three of the four arms had broken away from the structural casing of the machine, with their foldable joint locking collars still in place. The hinges of these three arms were surrounded by their collars and were undamaged. However, the fourth motor arm appeared to have broken at its hinge with its locking collar loose and the collar had then moved outwards, along the arm.
The damage to this arm suggests that the collar may not have been fully locked and had become loose during the flight. With a single arm not locked in place, it is probable this would result in variable thrust and cause the UA to become uncontrollable. However, this evidence is not conclusive, and the cause of this accident cannot be confirmed
=Damage to Airframe=
Per the above AAIB Report "Motor carrier arms broken from the casing"
Accident investigation:
 |
|
Sources:
1. AAIB Final Report: https://assets.publishing.service.gov.uk/media/620bb665d3bf7f4f065500b4/DJI_Matrice_300_171121_UAS_reg_n-a_03-22.pdf
2. https://en.wikipedia.org/wiki/Dursley
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 18-Jun-2023 19:21 | Dr. John Smith | Added |
| 18-Jun-2023 19:27 | harro | Updated |
Corrections or additions? ... Edit this accident description
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