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MANUFACTURING INNOVATIONS 18 MAY 2017 AIRCRAFT MAINTENANCE TECHNOLOGY conventional equipment. The use of the technique enables engineers to design the part the way it needs (author's emphasis) to be, rather than to accommodate traditional subtractive manufacturing [methods]." LEAP's vaunted 15 percent fuel burn savings ema - nates from two areas of the engine: Half comes from the high-pressure compressor, the other half from the fan. FANTASTIC FAN Based on what the company calls "fourth-generation aerodynamic design," LEAP features single-piece com- posite fan blades and fan case. CFM parent company Safran has been working on a way to fashion new fan blade resin for more than a quarter of a century. CFM doesn't detail just how the blades are manufactured. It does say the proprietary process entails weaving the carbon fiber on a three- dimensional loom, injecting resin and then baking the assembly in an autoclave. The final touch is application of a titanium leading edge. There's an old axiom in engineering that the fewer pieces a structure possesses the easier it is to maintain. LEAP's composite fan has a mere 18 wide-chord blades. That's half the number of the CFM56-5B and 25 percent fewer than the CFM56-7B. What airlines and aircraft leasing companies alike revel in the most, however, is this: LEAP burns 15 per- cent less fuel than its predecessor powerplant. Half of the 15 percent efficiency gain comes from propulsive efficiency — better aerodynamics. The fan is part 'n parcel of that. But there are also aerodynamic improve- ments in the core. The other half comes from thermal efficiency — operating at higher temperatures and pressure ratios. Although the LEAP engine does burn hotter than the CFM56, it is still below the GE90 and GEnx. The twist is that CFM has maintained the durability of the CFM56 family. The blades in the LEAP high-pressure turbine are made of the same material as those of the CFM56, but CFM has incorporated improved cooling technol- ogy and aerodynamics to maintain durability. Look at the temperature profile of a LEAP blade and a CFM56 blade. You can't tell the difference, which means it is more durable. That is another reason why the OEM contends maintenance costs will be on par with the current engine family. It's not as if massive, high-bypass ratio, other-than- metal fans are a new invention. Through its parent companies, GE and Safran, CFM has a world, quite liter- ally, of experience with big, lighter-weight fan blades fabricated from carbon fiber composites. Consider, the GE90 has been flying since the middle of the last decade of the century, 1995 to be precise. The engine has tallied in excess of 60 million flight hours. As of this writing, there have been zero ADs (Airworthiness Directives) covering the GE90's compos- ite fan blades, and a mere handful have been removed from service. The engine-maker asserts, "This is the kind of record we expect the LEAP engine to achieve." MRO AND LEAP As of this writing, CFM says it's booked orders for some 12,000 LEAP powerplants. The LEAP-1A was intro- duced into commercial service on the Airbus A320neo in August 2016. LEAP-1B is slated to see service power- ing Boeing's 737 MAXes this year. LEAP-1C should fly beneath the fledgling wings of the new COMAC C919 in 2019 or thereabouts. Although just a handful of airlines are actually operating Airbus neos so far, dispatch rates and other operational indices are impressive. Nine months into line flying, CFM said LEAP was flying 98 percent of available days. Some carriers are logging 11 flights per day and wringing out 25-minute gate turns. When the first LEAP comes off wing for overhaul, indications are there will be enough options to accom- modate the demand. Currently a trio of shops is certified to pull LEAP overhauls: Lafayette, IN; Brussels, Belgium; and San Quentin, France. All three are internal GE or Safran facilities. Third-party MRO shops have yet to be announced. "We are years away from the first LEAP overhaul," says CFM. These third-party announcements "will be made at some point in the future." Meanwhile, new LEAPs continue to flow from a key domestic facility: GE's Lafayette, IN, plant. Some 500 hot section modules — consisting of compressor, combustor, and high-pressure turbine — are being manufactured at GE's U.S. facility. THE LEAP-1A powers the A320neo family. CFM INTERNATIONAL JEROME GREER CHANDLER is a two-time winner in the Aerospace Journalist of the Year com- petition's Best Maintenance Submission category; he won in 2000 and 2008. His best- seller 'Fire and Rain' chronicles the wind shear crash of Delta Flight 191 at DFW. Chandler's passion for aviation safety is more than professional. It's personal. Two of his relatives have perished on commercial airliners, one of them in the infamous Braniff Electra crash of 1959.