Boeing 777X Testing Paused and Test Fleet Grounded

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The Boeing 777X program has faced another setback after a post-flight inspection of one of the aircraft led to the discovery of a failed engine mount, pausing the certification campaign of the type.

Affecting multiple 777Xs

According to a report by The Air Current, Boeing was forced to suspend the flight certification of the 777X after the manufacturers technicians had discovered a severed thrust link on WH003, one of the testbeds of the type.

The aircraft, registered as N779XY, had just completed a more than five-hour test flight in Hawaii. Flightradar24 data showed that the 777X departed and arrived back at Kona International Airport (KOA) on August 15.

Following the five-hour and 31-minute test flight, the aircraft has remained on the ground since August 15, the flight tracking sites records indicated.

The Air Current, citing people familiar with the matter, added that another two 777Xs were affected by the same issue, with cracks being found on the pairs engine mounting structure.

In a statement to Simple Flying, a Boeing spokesperson said that its technicians identified a component that did not perform as designed, with the engineers replacing the affected part.

The aircraft manufacturer will capture any learnings from the component and resume flight testing when ready, the spokesperson added.

Certification campaign paused

In total, Boeing has four 777Xs for its flight testing campaign, which, following the Federal Aviation Administration (FAA) granting the Type Inspection Authorization (TIA) to the type, began certification flight testing in July.

The Boeing representative clarified that the company has been inspecting its flight test fleet for similar failures, adding that no flight tests were planned on other aircraft in the near-term future since the other 777Xs have scheduled maintenance and layup activities.

We are keeping the FAA fully informed on the issue and have shared information with our customers.

Each engine includes two of these components, so there was redundancy, with the part being custom to the 777-9, the spokesperson detailed.

In addition to N779XY, Boeing has N779XW, N779XX, and N779XZ as its testbeds for the program.

Photo: Tom Boon | Simple Flying

N779XW last operated a flight on August 12, completing a four-hour flight from/to Seattle Paine Field International Airport (PAE), while N779XX last flew on August 9, when it completed a return itinerary from Moses Lake Grant County International Airport (MWH) to Seattle Boeing Field (BFI).

Meanwhile, N779XZ last operated a flight almost three years ago. Flightradar24 data showed that the aircrafts previous flight was on November 18, 2021, when it was ferried from BFI to PAE. It briefly appeared on the radar on April 4, yet did not complete a flight on the day.

First delivery in 2025?

During Boeings Q2 earnings call with analysts on July 31, Dave Calhoun, the former president and chief executive officer (CEO) of the company, stated that the 777-9s had accumulated more than 1,200 flights and 3,500 flight hours (FH) in various environments.

Photo: Jonathan Hendry | Simple Flying

Brian West, the chief financial officer (CFO) and executive vice president of finance of Boeing, reiterated that the aircraft manufacturer will continue following the FAAs lead, expecting to deliver the first 777X to a customer in 2025.

This post was brought to you by Simple Flying. Written By Rytis Beresneviius.

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