Boeing may resume the flight test programme for the 777X soon after grounding its four testing airframes in August 2024 owing to a problem with the type’s thrust linkages.
Resuming flight testing
According to AviationWeek, Boeing plans to commence flight testing of the 777X, with the maiden flight possibly taking place as early as January 15 (at the time of publication, the flight had not yet occurred). The company halted the campaign after discovering damaged propulsion linkages on all four test planes in August 2024.
None of the four 777-9 test planes have flown since September 2024. Boeing’s final 777-9 flight occurred on September 8, 2024, when it transported the N779XY, also known as WH003, from Kona International Airport (KOA) to King County International Airport (BFI).
The airframe’s previous flight occurred on August 15, 2024, when it flew for five hours and 31 minutes near Hawaii, departing from Kona and landing at the same airport.
N779XX (WH002) and N779XW (WH001) last flew on August 9, 2024 and August 12, 2024, respectively, while N779XZ (WH004) hasn’t flown since November 2021. Flightradar24 records show that the later aircraft’s transponder briefly went online on April 4, 2024.
Boeing confirmed to Simple Flying in August that the severed propulsion linkages were detected during routine maintenance. The business changed the part and was capturing any learnings from the component, and it will restart flight tests when ready, according to the plane manufacturer’s representative. The Air Current was the first to report on the development.
However, a Boeing spokesman stated at the time that no near-term flying tests were planned for the other airframes – the first aircraft with severed thrust linkages was N779XY (WH003) – which were slated for maintenance and “layup activities.”
Terrific aircraft
On September 13, 2024, shortly after N779XY (WH003) returned to the mainland United States from Hawaii, Boeing’s CFO and executive vice president of finance, Brian West, spoke at the Morgan Stanley Laguna Conference. The incident began several hours after the manufacturer’s 33,000 machinists from many states began their strike, which would stretch until November 2024.
West explained that Boeing observed damage to one of the propulsion linkages on the flying test aircraft. In response, the aircraft manufacturer promptly halted the flying test programme, and its engineers began investigating the underlying cause and potential corrective actions to bring the 777-9 test fleet back in the air.
“Last week, you might have seen that the original airplane flew back safely from Kona to Seattle, and the team is well underway to work out those next steps. […] We have to give the team time to assess the situation and then a path forward.”
West concluded that Boeing continues to believe it is a great aircraft, and that its customers agree. The CFO stated that the corporation needs to resolve the flight test issue.
The impact was clear by the end of October 2024, when Boeing stated that the 777-9’s entry-into-service (EIS) date, which was originally intended for 2020, had been pushed back to 2026. As a result, the 777-8F’s EIS was also put back to 2028.
The delay led Boeing to take a $2.6 billion pre-tax profits penalty, which was based on an updated evaluation of the certification deadlines to account for delays in the 777-9 flight testing. The review also considered expected delays due to the International Association of Machinists and Aerospace Workers (IAM) strike.
Progressing through certification
Prior to the thrust link issue that grounded the 777X test flight fleet for months, Boeing had made steady progress towards the type’s certification. After receiving Type Inspection Authorisation (TIA) for the 777-9, flight tests commenced in July 2024 with representatives from the Federal Aviation Administration (FAA) on board.
The TIA shall be “used to authorise official conformity, airworthiness inspections, and flight tests necessary to fulfil certain requirements for Type Certificate (TC), Supplemental Type Certificate (STC), amended TC, and amended STC certification,” as defined by the FAA.
Boeing will update the 777’s TC to include the 777-9, “a derivative of the Boeing Model 777 aeroplane currently approved” by the FAA, according to a document issued by the regulator in August 2024. Prior to the thrust link issue, Boeing estimated that the 777-9 would begin service in 2025.
FAQ
Why is Boeing restarting the 777X certification flight tests?
Boeing is restarting the certification flight tests for the 777X as part of the final phase to meet all regulatory requirements and ensure that the aircraft is ready for commercial service. The tests are crucial for verifying the aircraft’s performance, safety, and compliance with aviation standards set by regulatory authorities like the FAA and EASA.
What is the 777X certification process?
The 777X certification process involves a series of rigorous flight tests designed to assess the aircraft’s systems, safety features, fuel efficiency, handling characteristics, and overall performance under various conditions. These tests are conducted to ensure the aircraft meets all required standards set by aviation regulatory bodies such as the FAA and EASA before it can be approved for commercial flights.
What is the status of the 777X program?
As of now, the 777X program has faced delays due to challenges with the aircraft’s engines and other design modifications. However, Boeing has resumed the certification flight tests, with the aircraft expected to be delivered to customers in the coming years once the testing is completed and certifications are granted.
When will the Boeing 777X enter commercial service?
Boeing initially aimed for the 777X to enter commercial service in 2021, but due to delays, it is now expected to enter service around late 2025 or early 2026. The aircraft’s certification and delivery timeline will depend on the successful completion of flight tests and regulatory approval.
What are the improvements of the Boeing 777X over its predecessors?
The Boeing 777X features a range of improvements over its predecessors, including larger, more fuel-efficient engines, new wing designs with folding wingtips for better aerodynamics, a wider cabin, and advanced technology for improved passenger comfort and operational efficiency. These features are aimed at enhancing performance, reducing fuel consumption, and improving the flying experience for passengers.
