Farnborough Air Show

CFM To Build 34K-pound thrust-rated Leap for A321XLR

 - July 18, 2022, 2:00 AM
The Airbus A321XLR will benefit from a more powerful Leap-1A turbofan under development by CFM. (Photo: Airbus)

CFM International will supply a version of the Leap-1A that generates 34,000 pounds of maximum takeoff thrust for highest-gross-weight or hot-and-high Airbus A321XLR missions, CFM president and CEO Gaël Méheust told AIN just ahead of the Farnborough Airshow.

Designated the Leap-1A35A, the highest-thrust version of the engine type-certificated by CFM so far will physically replicate all other Leap-1A engines and will obtain its thrust increase purely by means of a data plug that updates the engine control, according to Méheust.

While CFM already has included the Leap-1A35A in its EASA and FAA Type Certificate Data Sheets (TCDSs) for existing Leap-1A variants, the latest revision of the FAA TCDS (Revision 7) indicates that CFM so far has certified the Leap-1A35A for only 32,160 pounds of maximum takeoff thrust. That suggests CFM will need to complete a further certification exercise to increase the version’s maximum takeoff thrust to 34,000 pounds—though given Méheust’s unequivocal confirmation of the Leap-1A35A’s increased thrust level, the work might well prove minor and require CFM only to submit a paper analysis to the regulators.

CFM is “extremely proud that the Leap-1A was the first engine to fly on the A321XLR,” said Méheust, adding that the engines in the A321XLR flight-test program have “performed perfectly.” In advance of the A321XLR’s first flight and during the flight-test program, CFM has not performed any specific engine tests to support the A321XLR program, he said, because the engine is identical to all other Leap-1As already powering A320neo-family aircraft.

Méheust also revealed that the Leap engine family has passed the 20 million flight-hour mark in commercial service and achieved a dispatch reliability rate higher than 99.95 percent.

He said the 99.95 percent figure represents an even better average than that achieved by CFM’s production record-breaking first-generation engine family, the CFM56, over its nearly 40 years in service. Méheust noted it took the CFM56 25 years of service before its design reached the extremely high dispatch reliability for which the family has become known, whereas CFM has achieved equal dispatch reliability with the Leap family in just six years of commercial service.

On a rolling 12-month basis, inflight shutdowns of Leap engines occur only once in every one million flight hours on average, according to Méheust. The highest time on wing achieved to date by a Leap engine stands at 17,000 flight hours and counting, while the highest-cycle example has accumulated approximately 10,000 cycles.

The most publicized early-service Leap technical “teething issues” involved only a limited number of engines, and CFM has developed solutions it either has already retrofitted “or are about to be” or has identified design fixes and is working to retrofit them, said Méheust. The only remaining Leap reliability objective for CFM involves “work on a better time on wing for engines operated by customers in hot and harsh environments,” he added, identifying those customers as based in the Middle East “and to a lesser extent India.”

Méheust said the CFM56 family had accumulated 1.2 billion flight hours by the opening date of Farnborough Airshow 2022 and CFM has delivered more than 50,000 engines from the CFM56 and Leap families. Production of CFM56s has fallen to a residual level to support commercial spare-engine requirements and production of Boeing 737NG-based military P-8 Poseidon and E-7 Wedgetail aircraft, but (counting announced orders and commitments only) CFM’s Leap production backlog stands in excess of 10,000 engines, he said.

GE Aviation and Safran Aircraft Engines, the two CFM joint-venture partners, now have dedicated more than 1,000 engineers to work on CFM’s RISE next-generation engine technology development initiative, which involves more than 300 different tests across some 150 test vehicles, rigs, and assemblies, according to Méheust. Later CFM will move to building and testing entire engines, which it expects to begin flight-testing “in the middle of the decade.”

CFM has already completed wind-tunnel tests to understand the combined fan-and-stator vane interaction of its planned open fan architecture for an eventual production engine developed from its RISE studies, said Méheust. Engineers have designed the large stator vanes installed on the nacelle behind the 4-meter-long fan blades to “optimize the airflow throughout the engine,” he said, adding that CFM eventually expects to “qualify the open fan architecture as a new method of propulsion.”

Méheust revealed that within the RISE research and development program CFM also has completed testing scaled hybrid-electric power solutions for future production-engine designs. Although he wouldn’t confirm how CFM’s design obtains the required additional electrical power, he said CFM’s hybrid-electric architecture uses electrical power both to augment the thrust produced by the open fan for takeoff and other high-thrust phases of flight and to provide electrical power for other aircraft functions during flight.