'Bits and pieces started showering down' - man cutting grass injured by blade from drone

A  number of people were struck by debris from a delivery drone which made an emergency landing following an incident in North County Dublin more than two years ago.

Details of the incident, involving a GEN 3.8 unmanned aircraft, have been revealed in a report which has just been published by the Air Accident Investigation Unit.

According to the report, which runs to more than 20 pages, the incident happened after one of the eight propeller blades separated from the drone during an urban delivery flight at Tankardstown, Balbriggan resulting in severe vibrations to the drone.

The alarm was raised at around 4.51pm on July 14, 2022 - less than a minute after the drone, which was being controlled by an operator, had taken off from the roof of a multi-story car park.

After the on-board engine stopped working, safety procedures were initiated and the drone landed close to a footpath in a residential area with assistance of an emergency parachute which was deployed. 

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According to the report, a man mowing a lawn in his back garden suffered a minor injury after a propeller blade fell off a drone that was delivering a package to a customer. Another eyewitness, who was struck on the shoulder by a fragment of a propeller blade, told the AAIU that the drone "wobbled for a second and then bits and pieces started showering down."

Neither of the men required medical treatment

The report found the flight path of the drone from its operating base on the top of a multi-storey car park at the Millfield Shopping Centre in Balbriggan was selected to avoid groups of people and sensitive areas such as schools.

The AAIU noted the remote pilot (23) had received training from a training body recognised by the Irish Aviation Authority as well as completing a practical skill assessment, although the associated certificate was not issued until after the accident.

The operator, which was issued with a light UAS operator certificate in May 2021, ’ told investigators that a new bolt tightening procedure for propellers had been introduced a number of weeks before the incident and that it believed staff at the location tended to overtighten bolts.

It informed the AAIU that the bolt tightening procedure has since been revised and that all bolts which were being used at the time have been removed from service and destroyed.

"Subsequent to the accident, the operator redesigned the propeller hub with what was described as being a ‘failsafe’ mechanism which would prevent the separation of a propeller blade from the hub in the event of a retaining bolt failure," states the report.

The operator of the drone, who is not named in the report, was delivering small packages to customers in the Balbriggan area who order goods online through an app.