The National Transportation Safety Board has opened an investigation into the first test flight of Facebook's Aquila drone, after classifying a reported "structural failure" as an "accident."
Aquila is the flagship for Facebook's Internet.org project aimed at providing internet access to remote areas without resorting to expensive satellite launches, according to The Guardian.
In a July blog post, Facebook's head of engineering and infrastructure, Jay Parikh, said: "We’re encouraged by this first successful flight, but we have a lot of work ahead of us … In our next tests, we will fly Aquila faster, higher and longer, eventually taking it above 60,000 feet."
The test flight lasted for 96 minutes, which is three times longer than the flight plan called for. Martin Luis Gomez and Andrew Cox wrote that under the extended flight, they "were able to gather data on how the structure and autopilot responded under a range of real-world conditions."
"We are still [analyzing] the results of the extended test," Gomez and Cox wrote, "including a structural failure we experienced just before landing."
The NTSB classifies the "structural failure" as an "accident" which means there was "substantial" damage.
According to the Code of Federal Regulations, or CFR, which governs the NTSB, substantial damage would be classified as damage that "adversely affects the structural strength, performance, or flight characteristics of the aircraft, and which would normally require major repair or replacement of the affected component." Excluded from this definition are engine failure, "ground damage" to propellers, and "damage to landing gear, wheels, tires, flaps, engine accessories, brakes, or wingtips."
The NTSB has not released any preliminary details on the accident, according to Bloomberg.
The investigation marks the latest in a series of setbacks suffered by the Internet.org project. The Washington Post reports that in early September, a SpaceX rocket bearing an AMOS-6 satellite belonging to Facebook exploded on the launch pad. The explosion was caused by "an anomaly on the pad resulting in the loss of the vehicle and its payload," SpaceX said in a statement. A year earlier, Facebook CEO Mark Zuckerberg said the satellite would bring broadband to remote parts of sub-Saharan Africa.