777X gives embattled Boeing a boost

[Ref Flight International Magazine 4-10 Feb 2020]

Boeing’s flight-test 777X, a GE Aviation GE9X-powered twinjet, designated WH001, eventually took off from Everett’s Paine Field at 10:09 local time on 25 January.

The successful completion of the 777-9’s 3h 51min maiden flight. The aircraft spent much of the first sortie operating at around 15,000ft just west of the Grand Coulee Dam.

Facts about the 777X
The 777X builds on that success. The new variant has a 10cm (4in) wider cabin, more seating capacity, composite wings with folding tips, and 10% better fuel efficiency.

The 777-9, the first 777X variant to be developed, is 76.7m (251ft) long – about 3m longer than its predecessor, the 777-300ER. The 777-9 will have 7,300nm (13,500km) range and capacity for 426 passengers in two classes, compared with the 777-300ER’s 7,370nm range and 396-passenger capacity.

Boeing also intends to develop a smaller 777X variant called the 777-8, but last year paused that development for an unspecified period.

Under the airframer’s current plans, the 777-8 will be 69.8m long, carry 384 passengers and have 8,730nm range. By comparison, the predecessor 777-200 is about 6m shorter, carries 317 ­passengers and has a range of 8,550nm.

Rightly, flight testing of 777-9 was due to start in 2019 with certification following in 2020, but an issue with the 777X’s GE9X turbofans pushed the maiden sortie into this year.

That problem involved stator vanes in the GE9X’s high-­pressure compressor and resulted in hotter-than-expected exhaust gas temperatures, causing premature degradation of components. GE recalled four GE9X engines from Boeing last year and says it has fixed the issue.

Now, the manufacturer expects 777-9 deliveries to begin in 2021.

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