The world's largest plane engine just received certification to power the new flagship airliner Boeing hopes will be its redemption, the 777X

• GE Aviation's new GE9X engine just received clearance to fly by the Federal Aviation Administration.
• Boeing selected General Electric to build the engines for its new 777X in 2013 and the result would be the world's largest jet engine.
• The GE9X will exclusively power the 777X and offer increased fuel efficiency and over 100,000 pounds of thrust.

The world's largest plane engine was just cleared to fly by the Federal Aviation Administration, paving the way for the commercial launch of the world's largest twin-engine passenger jet in 2022.

General Electric's aviation subsidiary, GE Aviation, is celebrating the milestone with its massive new GE9X engine that will soon fly thousands of passengers around the world every day. It's the exclusive engine for the Boeing 777X, a next-generation version of the manufacturer's famed 777 wide-body aircraft used by the likes of American Airlines, British Airways, and Emirates.

Boeing first gave GE Aviation the exclusive contract to develop and build the engines for the 777X in 2013. A likely match, GE Aviation currently make the GE90 engines that are used by some airlines currently flying the 777, including Qatar Airways which operates the world's longest 777 route between Doha, Qatar, and Auckland, New Zealand.

The engine's certification brings Boeing one step closer to delivering the finished product to launch customer Emirates in 2022. The coronavirus pandemic has slowed enthusiasm for new aircraft deliveries but the 777X is a feat of engineering that offers a 400-seat passenger cabin and increased fuel efficiency at a time when airlines need it the most.

Take a closer look at the GE Aviation GE9X engine.

The 777X is slated to be Boeing's redemption after being plagued by problems on its 737 Max and 787 Dreamliner families, two revolutionary aircraft that haven't been able to stay out of the headlines in recent years.

A taxing Boeing 777X in Seattle, Washington.      JASON REDMOND/AFP/Getty

The world's largest twin-engine is chock full of interesting features, including a wingspan so large that it requires retractable wingtips so it doesn't hit other airplanes while taxiing.

A Boeing 777X aircraft preparing for takeoff.      JASON REDMOND/AFP/Getty

Read More: The third Boeing 777X just flew for the first time — take a look at the enormous new flagship Boeing hopes will be its redemption

But behind any great aircraft is an equally great engine, and that's where the GE Aviation GE9X comes in.

A Boeing 777X test flight.      Stephen Brashear/Getty

Boeing tapped General Electric to power the 777X in 2013, requiring a new engine for the next-generation plane.

A GE Aviation GE9X engine during testing.      General Electric

The massive engines are the exclusive powerplant for the 777X, having the world's largest twin-engine jet all to itself and vice versa.

A GE Aviation GE9X engine during testing.      General Electric

It's not an uncommon practice for an engine to have a monopoly on an aircraft, especially with the specialized next-generation aircraft from Boeing and Airbus.

A GE Aviation GE9X engine during testing.      General Electric

The Airbus A350 XWB, for example, only uses Rolls-Royce engines.

An Airbus A350-1000 XWB aircraft with Rolls-Royce engines.      Tom Buysse/Shutterstock.com

And GE Aviation didn't disappoint, giving Boeing an engine that boasts 10% greater efficiency compared to its predecessor…

A GE Aviation GE9X engine during testing.      General Electric

Source: General Electric

Over 100,000 pounds of thrust per engine….

A GE Aviation GE9X engine during testing.      General Electric

Source: General Electric

And the lowest noise level of any GE Aviation engine.

A GE Aviation GE9X engine during testing.      General Electric

Source: General Electric

It's the largest airplane engine ever built but the use of composites and 3D printing actually makes it lighter than if using titanium, found on predecessor engines.

A GE Aviation GE9X engine during testing.      General Electric

Source: General Electric

The list price for each engine is over $70 million and airlines make their own deals to buy the engines from GE Aviation, though some of the leverage is gone since GE is the exclusive engine manufacturer for the 777X.

A GE Aviation GE9X engine during testing.      General Electric

Source: General Electric

The engine is so large that GE Aviation couldn't help but show off some size comparisons.

A GE Aviation GE9X engine used exclusively on the Boeing 777X.      JASON REDMOND/AFP/Getty

With a 134-inch diameter, a 7-foot-tall person could comfortably stand in the engine cavity with room to spare.

The GE Aviation GE9X engine that powers the Boeing 777X.      TERRAY SYLVESTER/Reuters

In fact, it's around the same width as a Boeing 737 fuselage, one of Boeing's most popular airliners.

A GE9X engine is roughly the same size as a Boeing 737 fuselage.      General Electric

Keep in mind, a 737 seats six people across one row separated by an aisle.

A Southwest Airlines Boeing 737 interior.      Thomas Pallini/Business Insider

GE Aviation has already delivered 10 GE9X engines to Boeing's Everett, Washington facility for the 777X test aircraft.

A Boeing 777X equipped with a GE Aviation GE9X engine.      Boeing

Boeing has four test aircraft currently crisscrossing the country in preparation for its Federal Aviation Administration certification and entry into service in 2022.

Boeing's third 777X aircraft departing on a test flight.      Boeing

The first flight of the world's longest twin-engine jet took place in January 2020, and so began the flight-testing campaign.

A Boeing 777X aircraft departing Paine Field.      JASON REDMOND/AFP/Getty

The GE9X will be specific to the 777X but testing the engine required an even bigger aircraft, the venerable Boeing 747.

A GE Aviation GE9X engine during testing.      General Electric

GE Aviation uses the Queen of the Skies as a testbed aircraft for new engines to put them through their paces in the air.

A GE Aviation GE9X engine during testing.      General Electric

Flight testing began with the 747 in March 2018 with the GE9X racking up over 5,000 hours in the sky before even coming near a 777X.

A Boeing 777X taxing at Paine Field.      JASON REDMOND/AFP/Getty

Source: General Electric

In the course of the 5,000 hours of testing, the engine held up across 3,000 take-offs and landings.

A Boeing 777X aircraft.      LINDSEY WASSON/Reuters

Various conditions are simulated including icing and rain, while also testing the engine against debris.

A Boeing 777X taxing to the hangar.      TERRAY SYLVESTER/Reuters

GE Aviation has racked up billions in orders for the engines, with over 600 on order from the various 777X carriers. That's over $20 billion in orders before the first aircraft has even been delivered, with maintenance programs also bringing in additional revenue.

A Boeing 777X with its wingtips retracted.      TERRAY SYLVESTER/Reuters

The first users of the GE9X will be the 777X's launch customers including Emirates...

An Emirates passenger plane comes in to land at London's Heathrow Airport.      Reuters

All Nippon Airways...

An All Nippon Airways Boeing 787-9 Dreamliner.      YOSHIKAZU TSUNO/AFP/Getty

British Airways...

A British Airways Boeing 777.      Reuters

Qatar Airways...

A Qatar Airways Boeing 777-200LR.      Thomas Pallini/Business Insider

Etihad Airways...

An Etihad Airways Boeing 777 aircraft.      Thomas Pallini/Business Insider

Singapore Airlines...

A Singapore Airlines Boeing 777 aircraft.      Soos Jozsef / Shutterstock.com

Lufthansa...

A Lufthansa Boeing 747-8i.      Larry Downing/Reuters

And Cathay Pacific.

A Cathay Pacific Boeing 777 plane lands at Hong Kong International Airport.      Reuters

Boeing picking GE Aviation for the engine comes as no surprise since GE90 engines have been faithfully powering current-generation 777 aircraft.

A Boeing 777-300ER aircraft powered by GE Aviation engines.      Shutterstock.com

The pandemic has slowed Boeing's production schedule for the 777X and the first delivery isn't expected until 2022.

A Boeing 777X aircraft in flight.      Boeing

But when it is delivered, the world will look on as the world's largest plane carries the world's largest engines into the next era of aviation.

Boeing stages the first flight of its 777X plane outside Seattle,      Reuters