NASA says its experimental electric airplane has taken a “major step” toward its maiden flight after successfully completing thermal testing of its cruise motor controllers.

The space agency has been working on the fully electric X-57 Maxwell aircraft since 2016 with the goal of creating an efficient and quiet flying machine that’s kinder to the environment.

In a recent blog post, NASA explained that thermal testing of the cruise motor controllers is vital “because it validates the design, operability, and workmanship quality of the controllers,” describing them as “critical components for providing power to X-57’s experimental electric motors.”

It added that complex systems such as these have temperature-sensitive parts and therefore it has to be confirmed that they’re able to safely handle extreme conditions during flight.

The controllers were recently put through their paces inside a test chamber at NASA’s Glenn Research Center in Cleveland, Ohio. Temperatures inside the chamber were set at a level to replicate what the X-57 could experience in flight: minus 11 degrees Fahrenheit to minus 147 degrees Fahrenheit (minus 23.9 degrees Celsius to minus 99.3 degrees Celsius).

Having confirmed the ability of the controllers to handle the challenging temperatures, NASA’s X-57 team is now moving toward combining all of the plane’s systems to ensure they’re able to function as one, a process that NASA describes as “one of the biggest challenges for an aircraft, especially a one-of-a-kind X-plane.”

The aircraft is being built by modifying a baseline Italian Tecnam P2006T aircraft, adding an electric propulsion system that features lithium-ion batteries together with 14 electric motors and propellers.

A date has yet to be set for the X-57’s maiden flight, however, the aircraft now faces a Flight Readiness Review at NASA’s Armstrong Flight Research Center in California.

NASA tweeted this week that X-57 pilots will use a 4K augmented-reality display instead of peering out from a conventional cockpit window. “Some rescue helicopters are already implementing this tech to help navigate crowded airspaces,” it said.

The unique design of @NASAAero's X-59 aircraft means pilots will use a 4K augmented reality display rather than a cockpit window. Some rescue helicopters are already implementing this @NASASpinoff tech to help navigate crowded airspaces: https://t.co/K1dxcOREAS pic.twitter.com/JdRDVtZxF6

— NASA (@NASA) February 7, 2023

The aviation industry is looking increasingly toward electric technology for powering aircraft. United Airlines, for example, two years ago invested an undisclosed amount in Swedish firm Heart Aerospace, which is developing an electric plane with a range of 250 miles.