CFM International predicts a $3 million to $4 million advantage in net present value for each A320neo powered by a Leap-X instead of a Pratt & Whitney PurePower PW1200G geared turbofan.
The cost claim announced at the CFM press briefing on 7 July marks CFM's most public attack on the fuel burn and maintenance cost promises made by P&W on behalf of their new turbofan that is assisted by a direct drive gear system.
So far, both engine makers have struggled to establish a dominant position on the one narrowbody platform - the A320neo - where each is offering a new product.
Airlines that have made engine selections on A320neo orders are split almost evenly between the two products, with the Leap-1A enjoying a tenuous 2% edge.
Since both engines remain in development, airlines are making decisions based on the engine maker's promises instead of operational data.
In private discussions with airlines for the past 18 months, CFM has touted its analysis of the Leap-1A's cost savings, but until now remained largely silent in public forums.
"Maybe we were too shy at the beginning [of the Leap sales campaign]", says Jean-Paul Ebanga, CFM chief executive officer.
CFM predicts the Leap-1A will deliver a 1.5% fuel burn advantage and require 50 fewer maintenance man-hours per aircraft each year, CFM says. Over a 15-year aircraft lifespan, those two factors alone account for a $3 million to $4 million advantage in net present value compared to the same A320neo powered by the competition, CFM says.
P&W has not publicly released a similar estimate of its net present value analysis of the PurePower engine family, but has claimed the engine family will generate a fuel savings of $1.5 million per aircraft per year when compared to "today's best airplanes".
Meanwhile, CFM also has started releasing drawings to suppliers to begin building the components for the first Leap engine-powered aircraft made in either Europe or China.
The General Electric/Snecma joint venture completed the design freeze milestone, or Tollgate 6 in CFM nomenclature, on 28 June for the Leap-1A and Leap-1C.
The Airbus A320neo is powered by the Leap-1A and the Comac C919 is driven by the Leap-1C, but both engines have identical turbomachinery.
The two aircraft types are each scheduled to enter service in the second quarter of 2016.