The U.S. National Transportation Safety Board (NTSB) is investigating an accident involving an experimental drone Facebook is developing to bring the internet to remote areas of the world. No one was hurt in the incident, which came during the unmanned aircraft's first test flight on June 28. The aircraft was designed to be used in Facebook's program to wirelessly connect the world. Earlier this year, an explosion had destroyed one of its satellites and political resistance to the service in India.

The high-altitude drone, which has a wingspan wider than a Boeing 737 and is powered by four electric engines, suffered a "structural failure" as it was coming in for a landing, according to a previously undisclosed investigation by the National Transportation Safety Board.

"We were happy with the successful first test flight and were able to verify several performance models and components including aerodynamics, batteries, control systems and crew training, with no major unexpected results," Facebook said.

Facebook added that the drone, called Aquila, had had a structural failure in a July 21 web post.

The accident occurred at 7:43 a.m. local time near Yuma, Peter Knudson, NTSB said.

The accident was the second involving an unmanned aircraft designed to fly for long periods as a less expensive alternative to satellites. An Google drone known as the Solara 50 was destroyed May 1, 2015, at a desert landing strip in New Mexico after experiencing control problems as it flew in a thermal updraft, according to the NTSB.

Facebook is developing to bring the internet to remote areas of the world.

No one was hurt in the incident, which came during the unmanned aircraft?s first test flight on June 28. The aircraft was designed to be used in Facebook?s program to wirelessly connect the world. Earlier this year, an explosion had destroyed one of its satellites and political resistance to the service in India.

The high-altitude drone, which has a wingspan wider than a Boeing 737 and is powered by four electric engines, suffered a "structural failure" as it was coming in for a landing, according to a previously undisclosed investigation by the National Transportation Safety Board.

"We were happy with the successful first test flight and were able to verify several performance models and components including aerodynamics, batteries, control systems and crew training, with no major unexpected results," Facebook said.

Facebook added that the drone, called Aquila, had had a structural failure in a July 21 web post.

The accident occurred at 7:43 a.m. local time near Yuma, Peter Knudson, NTSB said.

The accident was the second involving an unmanned aircraft designed to fly for long periods as a less expensive alternative to satellites. An Google drone known as the Solara 50 was destroyed May 1, 2015, at a desert landing strip in New Mexico after experiencing control problems as it flew in a thermal updraft, according to the NTSB.