Airbus chief operating officer customers, John Leahy cited his "reliable sources" at airlines and suppliers who have said Boeing's clean sheet New Small Airplane (NSA) wasn't fully off the table as the US airframer works to evaluate the configuration of its re-engined 737 Max.
"The clean sheet of paper team has not been dismantled in Seattle and...people are concerned as it takes longer and longer to get the Max into a condition [where] it can be competitive with the Neo that perhaps they would go back to - what until a couple months ago they were saying was their preferred choice - a clean sheet of paper airplane," said Leahy during a presentation in Washington, DC on the Airbus global market forecast for North America.
Boeing disputed Leahy's claim, saying that it was "absolutely" 100% committed to building the 737 Max, for which the company holds over 700 commitments from nine customers after it was officially launched in late-August. The airframer expects it first firm 737 Max order before the end of the year.
Boeing said its normal product development activities are on-going and the company is "always looking to what's next" for new programmes, architectures, production systems, technologies, configurations and markets.
Leahy also said that it would "not be a disaster" if Boeing switched back to a clean-sheet narrowbody to take on the A320neo, which will enter service with Qatar Airways in October 2015, citing the cushion of more than 1,450 firm orders and commitments for the re-engined A320 jet, including 1,200 firm orders.
Leahy said empty weight growth of the 737 Max, which he said could top 2.3t (5,000lbs), has eaten into the fuel burn improvement from its 173cm (68in) CFM International Leap-1B fan, which he claimed would only generate an 8% fuel burn improvement over today's 737.
Leahy also said the 737 Max will have a 7.5-8.5:1 bypass ratio compared to an 11:1 and 12:1 ratio on the A320neo's 198cm (78in) CFM Leap-1A and 206cm (81in) Pratt & Whitney PW1100G engines, respectively.
Airbus said its A320neo with 150 seats claims a 7% per seat fuel burn advantage over the 737-8 [re-engined 737-800] with 157 seats, while Boeing has said its 737-8 with 162 seats holds a 4% per seat fuel burn advantage over the 150-seat A320neo and 16% over today's A320.
Boeing said its 737 Max will garner 10-12% better fuel efficiency over today's Next Generation 737 family. The US airframer also claimed current model 737-800s hold a 2% operating cost advantage over the A320neo.
Boeing expects to achieve firm configuration for its 737 Max in 2013, four years ahead of its 2017 service entry.
Leahy claimed every 2.5cm (1in) of fan diameter translates to .5% of specific fuel consumption improvement (SFC) and the 28-32% larger fans on the A320neo compared to today's A320 family aircraft correlate to a 7% SFC improvement, while an additional 7% will come from the engine's core. About 1% additional SFC comes from the integration of the engine's new pylon and nacelle.
The total combination of the core, fan and integration gives the A320neo a 15.3% improvement in SFC, while its Sharklet wingtip treatments will deliver a further 2.4% SFC improvement over 1480km (800nm) stage-lengths, said Leahy.
Overall, the 1.6t (3,500lb) increase in the empty weight of the aircraft and the added drag of the larger Leap-1A fan would increase fuel burn by 2.7%, resulting in the A320neo's 15% improvement over today's CFM56-powered A320.