
Everything that has happened to this point — the hundreds of hours of bombardment with ice, the exposure to dust and debris that simulated 3,000 takeoffs and landings — was just the prelude. In recent weeks, the GE9X, the largest jet engine ever built, has started its certification testing at GE Aviation’s bootcamp for jet engines in Peebles, Ohio. When testing is complete, the GE9X will be approved by the FAA to fly on commercial jets.
The GE9X will power Boeing’s next-generation 777X passenger jet, but the path to get there is long and winding. The first build of the GE9X, catchily named FETT, or first full engine to test, took up residence at Peebles in March 2016 for a battery of tests at a cost of $1 billion.
The trials included icing tests that lasted for 168 hours and gathered data on more than 50 testing points. FETT spit out many terabytes of data during the tests, which lasted a total of 335 hours. Engineers took the lessons from those tests to build the engine that is being tested now.
“By incorporating all the learnings from the FETT engine, we start the GE9X certification program with a stable configuration and position ourselves to meet the schedule and performance expectations of our customers from Day 1 of service entry,” said Ted Ingling, GE9X general manager at GE Aviation.

Top: The GE9X at an ice test stand. Above: As large in diameter as the body of an entire Boeing 737, the GE9X is the biggest jet engine in the world. Images credit: GE Aviation.
The engine now on the test bed is nicknamed SETT, or second engine to test. The third engine is currently being built at GE Aviation’s headquarters in Evendale, Ohio and and a fourth will be installed before the end of the year on GE’s 747-400 test bed in the Mojave Desert. In total, eight GE9X engines will be used in the certification program.
The maturation testing of the engine started six years ago on at the component level. The engine will feature fourth-generation carbon fiber fan blades and a fan case, 3D-printed fuel nozzles and lightweight materials called ceramic matrix composites. The combination of these components decreases engine weight, boosts efficiency and will decrease fuel burn.
Nearly 700 GE9X engines already are on order.