Google sister company Wing has been making steady progress with tests involving its delivery drone in Australia, but a recent accident highlights some of the challenges facing such pilot projects as they attempt to go mainstream.

The mishap occurred when a Wing drone on its way to deliver a food order to a customer in Logan City, Brisbane, crashed into an 11,000-volt power line. The collision caused a small fire as the drone fried on the wire before falling to the ground, leading to the disruption of electricity supplies to around 2,300 homes and businesses.

The crash itself didn’t knock out the supply, but operator Energex decided to switch it off so it could safely examine the extent of the damage caused by the accident, ABC reported. The outage lasted 45 minutes for most of those affected, though 300 customers located near to the accident site had to wait three hours for the service to be restored.

A spokesperson for Wing told the news outlet that the drone had been attempting to make a “precautionary controlled landing [but] came to rest on an overhead power line.”

The spokesperson added: “We immediately reported this to Energex, who attended the location. Two hours later, during the retrieval process, there was a power outage in the area.”

The Alphabet-owned company apologized for any inconvenience caused and said it was conducting a review to find out how a drone on its way to make a delivery ended up incinerating itself on a power line.

Last year, Wing said Logan City had “a strong claim to be the drone-delivery capital of the world” for the large number of deliveries — around 4,000 a week — that its drones were making in the area.

Wing’s delivery drone pilot projects partner with local businesses and let select customers use their smartphones to order items such as snacks and over-the-counter pharmaceuticals. A drone then flies to the customer’s address and lowers the order down on a tether into their yard. With fewer emissions and faster delivery times over road-based deliveries, Wing believes drones are the way forward when it comes to getting smaller items into the hands of customers.

But clearly, there are still a few creases that need ironing out before such services are ready for prime time.

This recent calamity, for example, will come as an embarrassment to Wing, which needs to get communities onside if it’s ever to be allowed to operate its delivery drones in urban areas on a more widespread basis. In recent years, some residents in Australian neighborhoods where Wing has been testing its drones have been unhappy about the noise created by the machines. In response, Wing engineers created a new version of its drone that flies more quietly. Now it just needs to make one that avoids power lines, too.