CERTIFICATION testing of the General Electric GE90-powered Boeing 777 is expected to be completed around 7 November, boosting hopes that the delayed first delivery to British Airways could be made by 15 November.

Boeing has been conducting virtual round-the-clock flight tests of WA077, the second GE90-powered aircraft, and had completed around 240h of the required 300h functionality and reliability (F&R) flying by the time Flight International closed for press. The test team was still hunting for conditions to evaluate the wing thermal anti-ice system. The F&R continued after Boeing successfully re-tested the modified GE90 inlet acoustic panels which replaced the original units damaged when the 777 was tested for natural icing.

Boeing is believed to be defining the maximum gross take-off weight (MGTOW) of the 777-300 increased-gross-weight version to enable powerplant manufacturers to plan for accurate engine growth. The basic -300 has a 10,550km (5,500nm) range and a MGTOW of 299,370kg. The 777's wing design load is limited to a maximum potential MGTOW of around 326,880kg. The study is due to be completed by the end of the year and will indicate if the engine makers should aim for power plants in the 436kN (98,000lb) or 467kN thrust bracket.

In response, GE is planning a series of component tests in 1996 to determine growth steps for the GE90. Testing of the first growth engine, the GE90-92B has meanwhile begun at the engine company's test site in Peebles, Ohio.

The 1996 tests will determine whether the basic architecture of the engine can support growth to thrust levels as high as 467kN.

Pratt & Whitney has completed the first two major test phases of the 400kN PW4090, the first growth version of the PW4084. P&W says that a series of runs at sea-level and preliminary altitude tests at the Arnold Engineering Development Center in Tennessee show that the engine is "right on schedule" for certification in mid-1996.

Source: Flight International