GE Aviation is redesigning a static compressor part for the in-development GE9X engine, to power the Boeing 777X, after the component showed premature deterioration during the test programme.
The engine maker's chief executive David Joyce said during a briefing today that extended block cycle tests showed that the part "near the [compressor's] front end" proved to be less durable than expected and that this issue would, if unaddressed, lead to premature shop visits.
The problem was detected in late May when exhaust gas temperature readings were outside an expected range.
GE will install a re-engineered, "more robust" part in all eight engines involved in the GE9X test programme, Joyce says.
The part in question is being produced by GE rather than an external supplier, he notes.
Ground tests with the re-engineered part are being conducted, but the findings suggest a delay in the 9X programme.
Vice-president of commercial engines Bill Fitzgerald says that the manufacturer is still in the process of determining a flight test schedule for the modified engine.
He expresses confidence that the GE9X will be certificated "later in the fall" and that Boeing will still conduct the 777X's first flight this year.
The durability issue was determined during the last module of ground tests. That module – comprising around 250-300h of testing – will need to be completed prior to certification.
Fitzgerald foresees that the repeat test will "probably" begin in August.
Thus far, the GE9X programme accumulated around 2,700h of ground tests and an additional 450h across two flight-test campaigns on the manufacturer's 747 test bed, across a total of 71 sorties.