Mechanical engineer Jean-Noel Mahieu is leading design of the fan that will propel a markedly different powerplant than any CFM has produced before - the open rotor engine.

Why pioneer such a radical architecture path?

"The automobile had to undergo a new concept to keep making progress," he explains. "For us it's the very different architecture of an open rotor engine."

After 35 years, CFM's refinement of the turbofan is reaching a level of sophistication that precludes huge advances. In past years CFM has been able to lower fuel burn by about one percent each year through upgrades. The new LEAP-X turbofan, poised for 2016 certification, will reduce fuel burn by 16 percent compared to today's CFM56 engine.

But the industry will demand more dramatic advances in future decades, and an open rotor engine could cut fuel burn as much as 26 percent.

A counter-rotating fan built from woven composite material will distinguish the open rotor. The fan's blades (currently 12 in the front row and 10 in the back) are more peculiar than turbofan blades and must be guarded from different mechanical problems.

"CFM is investing a huge amount of time and resources into these blades," Jean-Noel says. "We're re-doing all our designs around new specifications."

Jean-Noel says their work is more fruitful because some of the best engineering minds in France and the U.S. are combining their knowledge. Both GE and Snecma, CFM's parent companies, are refining and testing their own open rotor geometries and then comparing results. "This teamwork is making it easier for CFM to determine the best open rotor design," says Jean-Noel.

The right design will include the most environmentally sound and fuel-efficient fan yet, with no compromise to CFM's established reliability.

Getting tough with carbon dioxide

Jean-Noel is not only facing a technical challenge as he works on the open rotor fan. He is also fighting the impact this engine will have on the planet.

"Pollution from airplanes affects the public," he says. "We have to address the problem of carbon dioxide emissions or we will be facing a bigger environmental problem. It's the only way to go on flying."

An open rotor engine promises to fly in dramatically cleaner fashion, and that's why Jean-Noel likes the new concept so well. Its efficiency is also a shield against that fitful foe of engine operators: fuel prices.

Better fuel burn

The fan plays a pivotal role in overall fuel efficiency because it produces 75 percent of an engine's thrust.

Composite materials are extremely light, allowing a higher bypass ratio and leading to lower fuel burn. Since they can be intricately formed, it is easier for Jean-Noel's team to mold the composite blades into aerodynamically efficient shapes.

A different type of noise

Because it operates at a less rapid speed, the noise frequencies from an open rotor engine are lower than what people are used to hearing from a traditional turbofan.

"The way people see and hear this engine will be different," Jean-Noel says. "We're doing a lot of simulation to determine how acceptable low frequency noise will be and how much we can diminish the sound."

His team is finding the best blade shape to get control of the noise. They're still making calculations to decide the number of blades per stage and the distance between them. The right configuration will deliver high fuel efficiency at an acceptable noise level.

Another way to dampen the noise is by tweaking the structure around the engine - a joint effort with aircraft manufacturers.

Tremendous durability

Above all, Jean-Noel's gravest responsibility is engine safety. "I take the technical quality of our designs very, very seriously," he says.

When a CFM56-powered aircraft encountered a flock of Canadian geese and made an emergency landing on the Hudson River in 2009, the event spurred Jean-Noel's team into more intense efforts to design robust fan blades.

They've increased the mass of engineering testing on designs and are taking into account bigger bird populations and the higher possibility of impact

Thankfully, woven composites are tough material. "We're already in front of the certification agencies in terms of durability," Jean-Noel promises.

Hearing what stakeholders say Jean-Noel says engine operators will have three things foremost on their minds during the next decade: safety, fuel efficiency and quiet operation.

He believes CFM is an industry leader that is responding to these needs. And more importantly, a leader that wants to work with every stakeholder.

"This is common work," Jean-Noel says. "We have to get together with customers, authorities and airplane makers to focus on the same goal. I'm confident that we can introduce a nice, safe product to the market."