Boeing has temporarily paused 777-9 test flights due to an unspecified issue with the General Electric 9X engine. Both Boeing and GE Aerospace have launched a joint investigation into the problem.

Boeing has manufactured four 777X test aircraft, however, since August only the 777-9, with registration N779XW, remained in flight testing. In November of 2021, the N779XZ prototype took off for the last time, on a flight between Seattle and Everett. Later in July, the N779XY prototype was also grounded whereas the N779XX prototype landed in Seattle the following month and has been grounded since then.

Recently, in an interview with aviation journalist Andreas Spaeth, as shared by Aerotime, Emirates’ president Sir Tim Clark explained that an engine glitch had been a problem.

“We know there was an engine glitch in October. They stopped the test program – not that there was much going on anyway. They dropped the engine, took it to General Electric in Cincinnati, and on December 6, 2022, we will get a heads up on what the problem is. Until then we wait for the results of the breakdown of the engine.”

Sir Tim Clark said to Andreas Spaeth

First 777X Delivery

Clark further stated that if the engine problem was serious, it would further push back the FAA approval for the aircraft. Emirates currently aims to take delivery of its first 777X aircraft in mid-2025.

“The July 2025 delivery date we estimate is something I said, not Boeing. They said they want to deliver by the end of 2024 or the first quarter of 2025. I said judging by their performance today, we make that July 2025. And Boeing Commercial CEO Stan Deal agreed. But the aircraft is over five years late and, if it continues to be late, our patience will be truly tested. We have an aging fleet, which needs to be replaced,” Sir Tim Clark said to Spaeth.

First Boeing 777X for Emirates Nears Completion
Emirates 777X winglet

Boeing is hopeful that the test program will resume in the summer of next year, but it depends on what the engine findings are, following the most recent glitch. However, if the problem is serious and it requires a redesign, it will become more complicated.

Earlier in its production, the GE9X engines installed on the 777X prototype suffered a compressor anomaly that occurred with another engine during pre-delivery tests, and the maiden flight was delayed while the engines were being modified to a final certifiable configuration.

After a delay of several months required to develop and test fixes to the GE9X, Boeing said that the GE9X engine issue would further delay the maiden flight until 2020. The issue led to a redesign of the compressor, which delayed the program by six months.

Boeing And GE Aerospace Confirmation

Both Boeing and GE Aerospace are working closely to identify and solve the problem as soon as possible, aiming not to miss the delivery date this time. Boeing provided the following statement regarding the engine problem:

“We are supporting GE Aerospace as they assess a recent GE9X engine issue and will resume airplane testing once their thorough process and appropriate actions are complete.

Boeing

“Safety is our top priority, and our supplier and technical teams will take the time necessary to support the review as we work transparently with our customers and regulators,” Boeing added.

GE Aerospace also confirmed the situation and said that the engine manufacturer “is reviewing a technical issue that occurred during GE9X post-certification engineering testing, and we are closely coordinating with Boeing on our findings to support their return to flight testing.”

Sources: Andreas Spaeth, Aerotime, Air Data News