General Electric plans to begin icing tests this month on the GE90-115B engine for Boeing's longer-range 777 family as part of efforts to recover from a two-week delay caused by the redesign of hot section baffles on the first test engine.
GE90 programme manager Chaker Chahrour says the issue was discovered after vibrations were detected in the engine towards the end of a 48h test phase. Borescope inspection revealed premature fatigue in air deflectors that divert cooling air to the high pressure turbine (HPT) discs.
The deflectors are anchored beneath HPT stator vanes, and appeared to be on the brink of failure "because they were not supported properly", says Chahrour. Although virtually identical to the deflectors on the baseline GE90, the newer units had been "simplified for easier maintenance".
"It put us out of commission for around two weeks, but we think we can recover from the delay," says Chahrour. The re-configured No 2 engine was due to begin icing tests at Peebles, Ohio, as Flight International went to press. It is expected to be joined by the modified No 1 engine within days. "So by 21 February we think both will be running," he says.
Six GE test engines, plus seven Boeing flight-test engines are planned, and the fourth will be the first GE90-115B to fly on GE's Boeing 747 flying testbed at Mojave, California, in May.
GE says that delivery to Boeing of the first flight test engines are on track for September, prior to roll-out of the initial 777-300ER in October.
Major assembly of the -300ER is expected to start in June this year, with first flight tentatively scheduled for 8 January next year. First -300ER deliveries begin in October 2003.
Work on the ultra-long-range -200LR, which was delayed 18 months following the 11 September terrorist attacks, has slowed to a trickle, with around 10% completed.
Source: Flight International
