MIAMI — Boeing has successfully carried out the first engine run of the 777X program, signaling that the first flight of the upgraded Triple Seven passenger plane, scheduled to happen in June, is imminent.

As every brand-new engine does, turning it on produces a thick puff of smoke. According to Katie Bailey, also known as KPAE Spotter, the excitement among the several aviation enthusiasts who witnessed the engine coming to life was evident.

According to Matt Cawby, a local spotter from Paine Field Airport, the testing lasted three hours.

The enormous General Electric GE9X is the world’s largest aviation engine in diameter, crafted especially for the Boeing 777X program. The engine’s nacelle is more than 15 feet in diameter.

Read More: Boeing 777-9X Revealed To Employees (+Photos)

General Electric claims that this engine is going to produce savings of up to 10% in fuel burn, as compared to its predecessor, the GE-90 that’s currently powering all of the Boeing 777-300(ER)s worldwide.

Even though General Electric has carried out endless tests at its facilities and even on its 747-400 flying testbed, today was the first time the engine was turned on directly from the flight deck of the newest variant in the 777 family.

This is a remarkable milestone for Boeing, who launched the manufacturing process of the new 777 variant in October 2017 and completed the assembly of the first flight test 777X in November 2018. 

The manufacturer wowed the world with the rollout of the first 777X testbed vehicle, a non-flying airframe that would go through one year of static testing on the ground before further testbeds are allowed in the skies.

The 777X will be the longest commercial passenger plane ever seen, measuring 252 ft (77 m), also sporting two of the world’s biggest engines.

The airplane’s wingspan, boosted by the world’s largest folding wingtips, will measure 235 feet (72 meters), almost the same as the airplane’s length. The first foldable wingtip was unveiled to the world in late-September 2018.

The 777X program has scored 340 orders from numerous carriers, among which Middle Eastern giants Emirates and Qatar Airways are prominent buyers. First delivery is expected to happen by 2020.