Airbus and Boeing have a big dilemma on which engine technology they should select for the new aircraft generation to replace the best-selling A320 and 737 families: advanced but "conventional" turbofans or the futuristic-looking open rotor?
But do not expect any hard dates from either manufacturer here in Paris. There are still too many uncertainties. For CFM International, the joint venture engine maker from GE and Snecma, the message is that it will supply whichever type the airframers select. "We will be there with the right technology at the right time," says Olivier Savin, executive vice-president of CFM.
The problem for Airbus and Boeing is that some airlines are demanding a new narrowbody choice with radically improved economics sooner rather than later. CFM says it will be ready with its all-new Leap-X engine in 2016. This will offer up to 16% better fuel burn and 50-60% lower NOx emissions compared with today's best CFM56s.
But open rotor technology could offer a lot more. Fuel burn could be 26% better with NOx levels similar to Leap-X, although a CFM open rotor engine could not enter service until late into the next decade.
"The big go/no-go decision will be at the end of 2011 because we will have enough test data by then on open rotor [to know if it is viable]," says Savin. "On paper it is very attractive but we need to study it deeper."
This puts Airbus and Boeing at a crossroads. Should they go early and opt for the next generation of turbofans such as Leap-X, or should they wait for open rotor? Another option, as CFM president Eric Bachelet explains, is to re-engine existing A320s and 737s with the new turbofans.
"We're going to be in a very strong position regardless," says Bachelet.