Boeing has resumed 777-9 testing after pausing flight tests earlier this year due to an unspecified issue with a GE Aerospace GE9X powerplant.

The aircraft manufacturer confirms testing has restarted, and flight tracking websites show that one 777-9 from Boeing’s test fleet got airborne on 17 December.

“We have resumed airplane testing following our comprehensive safety process and appropriate mitigations while our supplier and technical teams continue their work,” Boeing tells FlightGlobal. “We’re supporting GE Aerospace as they continue to assess a recent GE9X engine issue.”

777-9 Farnborough 2022

Source: BillyPix

GE Aerospace says it ”continues to work closely with Boeing on all requirements necessary to support the 777X flight-test programme.”

Boeing does not confirm when testing resumed, but FlightAware’s flight tracking website shows that Boeing’s first flight-test 777-9 – an aircraft with registration N779XW – got airborne on 17 December.

The jet took off from Seattle’s Boeing Field, flew east into Montana, then returned to Boeing Field, landing about 1h 40min later, FlightAware shows.

The aircraft completed a similar flight two days later on 19 December.

Prior to those flights, none of Boeing’s four 777-9 flight-test aircraft had flown for months, and the company’s three other 777-9 test aircraft have still not returned to the skies, according to aircraft tracking services.

One of those jets last flew in August, one last flew in July and the other last flew in November 2021, FlightAware shows.

Late last month, Boeing and GE confirmed they had paused the 777-9 flight-test campaign due to what GE called a “technical issue that occurred during GE9X post-certification engineering testing”.

“We had a finding during a borescope inspection of a flight-test engine and decided with Boeing to remove the engine and send it to our test facility in Peebles, Ohio for engineering test runs,” GE said in November. “During these runs, a temperature alert was observed and the operator shut the engine down normally.”

The engine maker added that the problem affected its “highest-time” GE9X – an engine that had accumulated more than 1,700h of run time and more than 2,600 flight cycles.

The 777-9 programme remains delayed amid heightened certification scrutiny by the US Federal Aviation Administration.

Boeing now anticipates delivering the first of the type in 2025. The company says it continues “to communicate transparently with our customers and regulators on progress”.

Story updated on 21 December to include a comment from GE Aerospace.