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Originally published July 18, 2010 at 7:06 PM | Page modified July 18, 2010 at 8:05 PM

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Engine makers rev up technology for new narrow-body jets

The narrow-body contest pits Boeing against not only Airbus but new contenders Bombardier of Canada, COMAC of China and Irkut of Russia, all vying for a slice of what Boeing estimates is a $1.7 trillion market for 21,000 new planes over 20 years.

Seattle Times aerospace reporter

FARNBOROUGH, England — Though at least five airplane makers are preparing plans for the brewing narrow-body jet battle, there are just two contenders to supply the engines that will power those planes.

In separate lavish London hotel suites Sunday ahead of the Farnborough Air Show, Pratt & Whitney and CFM International pitched their exquisitely engineered wares, and trashed each other's technology.

Pratt's engine has a huge fan at the front and a gearbox to ensure it runs efficiently. But rival CFM's executive vice president, Chaker Chahrour, contended "a gearbox is a major driver of unreliability."

CFM, in turn, touts the technical merits of its engine core, in which air is highly compressed and heated. But Todd Kallman, president of Pratt's commercial-engine division, said that for CFM to match his engine's fuel efficiency, "they'll have to do things to the core that will impact durability."

The narrow-body contest pits Boeing against not only Airbus but new contenders Bombardier of Canada, COMAC of China and Irkut of Russia, all vying for a slice of what Boeing estimates is a $1.7 trillion market for 21,000 new planes over 20 years.

The timing has Boeing in a quandary. Company leaders say they will decide by the end of the year whether to put one of these new engines on the 737 around 2015 or to sit tight and produce an all-new replacement jet much later.

The new entrants in the field have already picked their champions.

The Pratt engine will power Bombardier's CSeries jets and Irkut's MS-21 jet family, as well as Mitsubishi of Japan's smaller MRJ regional jet.

The CFM engine will power COMAC's C919 jet family.

And Airbus reaffirmed this weekend in London that it is likely to re-engine its jet and to offer both engines.

Greater modification

Because the 737 wing is closer to the ground than the A320's, Boeing would have more difficulty fitting these bigger engines to its plane. Wing and landing-gear modifications would be greater and the diameter of the engine might have to be slightly smaller than is possible for the A320.


Both engine makers insist theirs offer significant fuel efficiency for the 737, though less than for a brand new airplane without constraints like wing dimensions.

"We'd have to work really closely with Boeing to see how big an engine we can get and what modifications will the aircraft have to enable us to get optimum size," said Bob Saia, who heads Pratt's next-generation engine division. "We can still provide good double-digit performance improvement."

Pratt has designed a revolutionary geared turbofan engine that promises to reduce fuel burn by 16 percent compared with current engines and to slash emissions and noise.

The key sales point is the size of the fan at the front of the engine. While the 737 engine today has a 61-inch diameter, the new engine could be around 80 inches.

By sucking air backward, the fan produces most of the forward thrust of any modern engine. A bigger fan can produce the same thrust with a slower and quieter flow of air.

"We're leveraging physics," said Saia. "Fundamentally, big fans are good for fuel efficiency and noise."

CFM, a joint venture between General Electric and Snecma of France, is offering an engine that is more evolutionary in development but that claims to match the Pratt engine's radical efficiency improvements.

The company dominates the current narrow-body engine market with its CFM-56 model, the sole engine on all Boeing 737s and on half all Airbus A320s and boasts unbeatable reliability.

For its new engine, the LEAP-X, CFM is combining the ruggedness of its high-cycle CFM-56 narrow-body engine, with the efficiency of the engine core developed for General Electric's leading wide-body engines on the 777 and 787.

The LEAP-X core, where the air volume passing through is compressed by a factor of 22, derives its efficiency from multiple technologies developed over more than a decade.

A rigid casing protects the inner parts when airplane maneuvers deliver high loads to the engine. Tiny blades on the inner spinning disks are shaped for aerodynamic efficiency.

In the combustion chamber the air is pre-swirled to mix better with the fuel.

A mix of ceramics and composites is used to line the inner shroud of the engine casing.

Last month, when Chip Blankenship, head of the commercial-engines division at GE Aviation, came to Everett for the first flight of the first 787 with a GEnx engine, he staked his claim that LEAP-X "is itself revolutionary technology."

"We've spent the last five years refining this high-pressure ratio compressor technology that we've put into the 787," he said. "We'll spend the next few years ruggedizing that based on our experience with the CFM56 and its high reliability. We'll marry those two approaches."

Saia said his Pratt engine has surpassed all expectations in demonstrator tests. It is scheduled to fly on the CSeries for the first time in 2012 and enter service in 2013.

Chahrour said the CFM engine also is passing all tests. It should be ready for service in 2015.

Dominic Gates: 206-464-2963 or

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