GE will soon begin flight testing the largest high-bypass turbofan in the world, the GE9X. Developed from the GE90, the GE9X, with a fan diameter of just over 11 feet and providing 105,000 lbf of thrust, is expected to deliver a fuel savings of 10-percent over its GE90-115B predecessor. The GE9X was developed to power the Boeing 777X, which Boeing touts as the largest and most efficient twin-engine airliner in the world. To match the gargantuan size of the engines, the 777's composite wings will have a span of 236 feet (72 meters) and will feature folding wingtips to allow it to park at existing airport gates. The two variants slated for production, the 777-8 and 777-9, will accommodate 365 and 414 passengers respectively.
GE is currently carrying out environmental and ETOPS static testing to achieve certification, and, in November, one engine was mounted to a modified Boeing 747 testbed for flight testing. To fit the huge engine, the 747 was given longer struts, larger tires, and a specially modified pylon. Even with these modifications, the massive GE9X has only 18 inches of ground clearance. Flight testing is scheduled to begin in late 2017, and the 777X is slated for rollout in 2019, with orders placed for 20 aircraft so far.