Boeing has resumed testing of the 777-9 after halting flight tests earlier this year due to unspecified issues with the GE Aerospace GE9X power plant.
The aircraft manufacturer confirmed testing had restarted, and the flight tracking website shows that one 777-9 from Boeing’s test fleet was in the air on December 17.
“We have continued testing the aircraft following our comprehensive safety process and appropriate mitigation while our suppliers and engineering teams continue their work,” Boeing told FlightGlobal. “We support GE Aerospace as they continue to assess the recent GE9X engine issues.”
GE Aerospace said it “continues to work closely with Boeing on all requirements necessary to support the 777X flight test program.”
Boeing did not confirm when testing resumed, but flight tracking website FlightAware indicates that the first test flight of the Boeing 777-9 – an aircraft with registration N779XW – was in the air on December 17.
The jet took off from Seattle’s Boeing Ground, flew east toward Montana, then returned to Boeing Ground, landing about 1 hour and 40 minutes later, FlightAware showed.
The aircraft completed a similar flight two days later on 19 December.
Prior to the flight, none of the Boeing 777-9’s four test planes had flown for months, and the company’s other three 777-9 test planes had still not returned to the skies, according to the aircraft tracking service.
One of the jets last flew in August, one last flew in July and the other flew last in November 2021, FlightAware showed.
Late last month, Boeing and GE confirmed they had halted the 777-9 flight test campaign due to what GE called “a technical issue that occurred during engineering testing post GE9X certification”.
“We got the findings during a borescope inspection of the flight test engine and decided with Boeing to remove the engine and send it to our test facility in Peebles, Ohio for engineering trials,” GE said in November. “During this run a temperature warning was observed and the operator shut down the engine normally.”
The engine maker added that the issue affected the “highest time” GE9X – an engine that has accumulated more than 1,700 hours of runtime and more than 2,600 flight cycles.
The 777-9 program remains pending amid increased scrutiny of certification by the US Federal Aviation Administration.
Boeing now anticipates delivery of the first type in 2025. The company says it continues to “communicate transparently with our customers and regulators about progress”.
Story updated on December 21 to include comment from GE Aerospace.