Initial test results of the Passport turbofan and its unusual one-piece blisked fan are on track and augur well for next year’s fast-paced development and certification phase, says .
The 16,500-pounds-thrust engine is expected to complete certification in 2015 and enter service on’s new Global 7000 and 8000 ultra-long-range corporate jets in 2016 and 2017, respectively.
Testing of the first engine got under way at GE’s evaluation facility in Peebles, Ohio, on June 24. A second engine joined the test effort in September, with a further six planned for the certification program.
“Next year is a big one for us,” says Judd Tressler, director of Bombardier programs for GE. The test rate is already building up through the remainder of 2013, he adds. “We will run a third fan blade out with a rig test coming up, the second engine has run, and the first has already gone back for crosswind tests.”
The program accelerates next year with the start of endurance tests and flight evaluations when Passport becomes the first engine to be tested on GE’s newly acquired-400 flying testbed.
“Overall, we’ll build up 4,000 hours and 8,000 cycles before entry into service. We have four in build now, as well as the two on test,” says Tressler, who acknowledges the program is not without issues. “Every day there’s a new challenge. We’re talking about things like instrumentation and challenges with clearances and the oil system. However, we haven’t had any one big thing that gets you to stop and do anything different. But at this point we’re fairly confident we can continue to meet our schedule. That’s the reason we test.”
First results are encouraging, adds GE. “We’re very comfortable with the performance of the machine. The operability and performance is tracking where we think we should be. We’re very optimistic about what we have,” Tressler says. “We demonstrated a maximum net thrust achieved of 19,200 pounds thrust, so we know the capability is there.”
Compared with its nearest competitor, theBR725, which powers the Gulfstream G650, GE says the Passport will have 8% better specific fuel consumption. The engine will also have margin to Stage 4 noise rules, and “we’ll be able to certify to CAEP/8 emissions regulations with no problems,” he adds.
The program follows three years of validation testing on several key technologies, one of the most distinctive features being the 52-in.-dia. blisked fan. The design is made up of a single integrated disk and set of blades rather than the conventional arrangement of blades slotted into dovetails in the disk. The feature showed immediate benefits from the start of testing, says Tressler. “With the first engine right out of the gate we didn’t have to adjust anything. In conventional fans the lube system between the fan blades and disk gets sticky over time, and eventually noise and vibration goes up. However, with this, once the trim is balanced, it is balanced.”
The engine also incorporates a composite fan case, similar to those developed for theengines in production for the and 787, and is encapsulated within an integrated propulsion system from Nexcelle, a joint venture between GE and . The configuration includes a low-drag, slim-line nacelle with outward opening cowl to reduce weight while allowing for easier maintenance access. Internally, the blisks and compressor blades are also coated in a smooth, impact-resistant surface finish to improve aerodynamic efficiency.
One of the most exotic features is the use of an oxide-oxide ceramic matrix composite (CMC) for the exhaust mixer, center body and core cowls. The lightweight, high-temperature-resistant material is well-suited for lightly loaded applications and is the first non-military GE engine with this technology, says principle engineer Bernie Renggli. “It’s two-thirds the weight of titanium, so we’re saving up to 45 pounds per engine, or 90 pounds per shipset.”