ASN Wikibase Occurrence # 315431
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| Date: | Monday 25 July 2022 |
| Time: | 13:00 |
| Type: | Evolve Dynamics Sky Mantis |
| Owner/operator: | Hertfordshire Fire & Rescue Service |
| Registration: | unreg. |
| MSN: | ED-SKM-2020-08-03 |
| Fatalities: | Fatalities: 0 / Occupants: 0 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Orient Close, St. Albans, Hertfordshire -
 United Kingdom
|
| Phase: | En route |
| Nature: | Survey |
| Departure airport: | Orient Close, St. Albans, Hertfordshire |
| Orient Close, St. Albans, Hertfordshire | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
AAIB investigation to Evolve Dynamics Sky Mantis, (UAS registration n/a): Loss of battery power in flight, St Albans, Hertfordshire, 25 July 2022.
The Evolve Dynamics Sky Mantis UAS was being operated in support of emergency services that were tackling a building fire in St Albans. The UA had successfully completed two flights at the site and was about 13 minutes into its third flight when, from a height of about 20 metres, it suddenly fell to the ground.
The aircraft was destroyed. The operator had a 200 m cordon in place and was operating the aircraft overhead waste land. No persons were injured.
The UAS operator had purchased the aircraft in 2020, which was supplied with five batteries. The operator’s procedures required that a weekly check flight was performed, which took place on the morning of the day of the accident. The aircraft’s battery was replaced prior to each flight on the day. These are referred to as ‘check flight’, ‘flight 1’, ‘flight 2’ and ‘accident flight’ batteries in this report. The pilot stated that he did not notice anything unusual during his checks of the aircraft between flights.
=AAIB Analysis=
The aircraft lost electrical power in flight and fell to the ground because of separation of electrical contacts between the aircraft and battery connections. The separation was a result of a loss of structural integrity due to thermal damage to the connectors.
The small scorch mark on the flight 1 battery indicates that the battery connector on the aircraft had been damaged at some point prior to, or during, flight 1. It was not determined as to how this occurred, but it is possible that foreign object debris could have entered the open battery compartment prior to fitting the battery, or that the battery was not fully locked into place during this flight.
Either possibility could have resulted in an increase in inter-contact resistances, causing temperature increases of the connector material that allowed pins to recede or be damaged. This damage eventually culminated in an electrical thermal run-away during the accident flight until pin separation occurred
=Safety action taken=
The manufacturer has updated the Sky Mantis Operations Manual to include an instruction during pre-flight to check that the aircraft and battery connections are clean and undamaged
Accident investigation:
 |
|
Sources:
1. AAIB Final Report: https://www.gov.uk/aaib-reports/aaib-investigation-to-evolve-dynamics-sky-mantis-uas-registration-n-slash-a-250722
2. https://www.hertfordshiremercury.co.uk/news/hertfordshire-news/live-st-albans-updates-explosion-7376669
3. https://www.watfordobserver.co.uk/news/20515983.st-albans-fire-50-firefighters-called-car-workshop/
4. https://www.bbc.com/news/uk-england-beds-bucks-herts-62292925
Media:
Big explosion in the industrial estate behind us off London road. Hope no one is injured. #stalbans #orientclose pic.twitter.com/fU2qKOdvEc
— Mat Oram (@mat_oram) July 25, 2022
Big explosion in the industrial estate behind us off London road. Hope no one is injured. #stalbans #orientclose pic.twitter.com/fU2qKOdvEc
— Mat Oram (@mat_oram) July 25, 2022
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 18-Jun-2023 19:20 | Dr. John Smith | Added |
| 18-Jun-2023 19:26 | harro | Updated |
Corrections or additions? ... Edit this accident description
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