Flight tests of the -2 PIP are meanwhile “going extremely well,” says Nugent. “The 747 flying testbed is about two-thirds of the way through its flights, and we're seeing excellent results in terms of performance. We were expecting to get 1.6% improvement in fuel consumption and, based on test data, we're optimistic we will be at or better than that.”
To combat the original fuel-burn shortfall of more than 2%, GE designed an all-new low-pressure turbine, and added compressor, combustor and turbine improvements from the 787 engine's PIP II upgrade. Together with better-than-expected 1% fuel-burn improvement seen by initial 747-8 operators on the baseline engine, added to airframe improvements instituted by Boeing, Nugent says the -2 PIP will bring the aircraft up to or beyond specification.
“The flying testbed shall wrap up in the next couple of weeks and will culminate with Boeing pilot demonstration flights in which we will do operability and air starts,” says GEnx-2B program manager Tom Walker. The final round of certification work includes endurance testing of the low-pressure turbine (LPT). “We do have some stress tests and vibration-system testing, but the key one is the LPT. It's not a full 'block' test, [an endurance test required for all new engines], since the low-pressure turbine is the same technology as the PIP II, so it is not 100% new.” GE hopes for engine certification by mid-year, clearing the way for deliveries on 747-8s by year-end.