Man injured by dropped drone propeller while mowing lawn, investigators say

A man was injured after a drone propeller fell on him in Dublin, according to a report by aviation accident investigators.

The incident occurred during an urban flight by the unmanned drone delivery company Manna in July 2022.

The Air Accident Investigation Unit released a report on the incident on Friday.

It was said that a propeller blade on the drone came loose during the flight, causing severe vibrations and subsequently causing an electric motor to fail.

This activated the onboard flight termination system and the deployment of an emergency parachute. The drone landed on the ground with minor damage.

Meanwhile, the propeller blade that had come loose hit a man on the ground.

The man told the inquiry he was mowing the grass in his backyard when he was struck by what he believed was part of a drone’s propeller.

He stated that he did not notice anything unusual before he was hit by the sound of his lawn mower. He said he suffered a small cut on his head but did not require stitches or hospital care.

( ‘We had 40 flyovers before 2pm’: West Dublin couple annoyed by delivery drones above their homeOpens in a new window )

The investigation revealed that the probable cause of the accident was a fatigue failure of a bolt securing the propeller blade, causing the blade to separate from the drone.

The drone did not have an airworthiness certificate, but was not required to have one.

The remote pilot had not been issued a certificate of completion of the practical assessment until after the accident, the report said.

The drone hit the ground in a public park and suffered some damage. The AAIU was not notified of the accident as required.

The propeller manufacturer stated that the polymer propeller used on the drone should not be used in a coaxial configuration. Manna then redesigned the propeller hub.

Manna has also committed to moving from the current coaxial configuration to a new design consisting of a single propeller mounted on each arm.

Manna said it appreciated the AAIU report and said the incident was “a controlled landing” and not a crash.

The company’s website states that drone deliveries are a “safer” alternative for delivery drivers because it results in fewer vehicles on the road and fewer accidents.

A statement said: “The report emphasizes that this incident was a unique, extraordinary event. We are pleased to report that we have had no issues with the integrity of the propeller since the event over two years ago.

“Following the incident, our company quickly implemented design and procedural changes to further enhance the safety and reliability of our operations.”

It added that the aircraft’s Flight Termination System activated as intended, deploying the emergency parachute to ensure a safe descent following a propeller failure. This system is specifically designed to prioritize the safety of people on the ground and to reduce any potential risk during an unexpected event.

“Our priority remains the safe and reliable delivery of goods to our customers, and we continue to work closely with the Irish Aviation Authority (IAA) to meet all regulatory standards.” – PA