See inside a test Boeing 777X, which has been further delayed to 2026 and annoyed its top customer --[Reported by Umva mag]

Flight Test 1 had flown more than 1,300 hours across some 540 flights, a flight-test engineer told Business Insider at the June 2023 airshow.

Each plane has its own purpose, focusing on a spectrum of items such as auto-land, environmental testing, low-speed performance, and extended dual-engine range operations.

The testbeds are essential for certification and help Boeing demonstrate to regulators the safety and reliability of its aircraft's technology and engines.

In August, 777X flight tests were paused after a problem was discovered in the structure that connects the engine to the plane.

"During scheduled maintenance, we identified a component that did not perform as designed," Boeing said in a statement shared with Business Insider. "Our team is replacing the part and capturing any learnings from the component and will resume flight testing when ready."

The twin-engine airliner will have a wingspan of 235 feet and five inches, which is longer than all previous 777 models.

The 23-foot-longer wings help generate more lift and improve efficiency by 10% compared to predecessors and competing aircraft.

Each aircraft type has specific airport requirements for everything from the width of the taxiways to the size of the gate, according to the Federal Aviation Administration. The above picture shows the space difference between an Air New Zealand Boeing 777 and a Lufthansa Airbus A340.

Boeing wanted to ensure the 777X wouldn't require new infrastructure, saving airports and operators time and money.

A longer wingspan generates more lift, improving performance and decreasing operational costs.

When the wingtips are retracted, the total wingspan is that of older 777 variants at about 212 feet.

James Hanley, a Boeing experimental test pilot, told Insider at the Farnborough Airshow in July 2022 that once the plane slows to about 50 knots, the wingtips would fold.

He added that because the folding mechanism couldn't occur until the jet reached the ground, it was a non-issue in the case of a go-around.

The aircraft is engineered to alert the pilots that wingtips are not extended before takeoff, whether that be via an alarm or auto-throttle not working, for example.

Moreover, the wingtips are part of the pilots' pre-flight checklist — adding another layer of safety.

It can also access things, including how well it can recover from an out-of-control dive or spin or how it performs flying through rough weather.

One is a series of black water tanks that can manipulate the jet's center of gravity.

The tanks located in the front and aft of the plane allow workers to transfer water back and forth to test the jet under different centers of gravity.

Engineers and pilots work together to plan and brief the tests, assessments, and goals for each mission.

Pilots will also relay information to the engineers, such as how the systems perform and if there are any human factors concerns, meaning how people interact with the machine.

"If the type of testing is kind of difficult on the body, we won't fly very long," the engineer said. "If it's fuel mileage testing, it's clearly going to be longer."

But the engineer added that there would be fewer people allowed on board during higher-risk tests.

The A350 competes with the 777X, but the 777-9 variant is bringing enhancements like bigger windows and more capacity.

The 777-9 can specifically fit up to 426 people in a two-class configuration with 10 seats across in economy. Airbus actually changed its A350 design to accommodate 10 abreast rows as a way to better compete with the 777X.

There were hundreds of feet of wire exposed, as well as insulation systems and other unique components that a typical airline passenger will likely never see.

The Air Current, which first reported the news, said that Boeing found issues with one of the parts on three of its test aircraft.

The part in question is a crucial piece of the structure that connects the engine to the plane.

Tim Clark said in a statement shared with Business Insider that because of inspection delays and ongoing strike action, "I fail to see how Boeing can make any meaningful forecasts of delivery dates."

Clark canceled 35 orders in late 2019, and he has since converted 16 of the 777-8 orders to the 777-9 — the former so far garnering less interest from customers.

Emirates expanded its order at the 2023 Dubai Air Show to a total of 205.

While American Airlines, Delta Air Lines, and United Airlines are still holding off, carriers including Air India, All Nippon Airways, Cathay Pacific, Etihad Airways, Lufthansa, Qatar Airways, and Singapore Airlines are all 777X customers.