GEnx-1B ETOPS certification on schedule despite turbine cracks

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General Electric has passed 2,000 cycles on its GEnx-1B extended operations (ETOPS) certification for Boeing's 787 and remains on track for completion in April, despite losing more than a month of testing after micro-cracks were discovered in one of the engine's high pressure (HP) turbine blades.

The cracks were discovered in January during a scheduled boroscope inspection as the engine passed 1,500 of its 3,000 ETOPS cycle testing.

Based on its engine maintenance manual, the engine HP turbine blade was deemed "unserviceable" and was removed from the test stand for repairs and resumed testing in late-February.

Because this was discovered on a single blade during a normal boroscope inspection similar to that of an operating environment, GE says, this is "something that would be expected in normal operation" and did not impact the operating of the engine and is not indicative of abnormal wear and tear.

As a result, GE says no design changes to the HP turbine, which are made from a proprietary powdered metal alloy, were required as a result of the discovery.

The engine-maker's baseline GEnx-1B engine configuration was undergoing testing, not GE's product improvement package (PIP1), which includes a revised low pressure turbine.

GE says the completion of ETOPS testing remains on track to wrap up in April, followed by an entry into service in the fourth quarter, a date that aligns with Boeing programme schedules that place the planned first delivery of a GEnx-1B powered 787 to Japan Airlines in October.