CFM International has initiated ground testing of the first all-new LEAP-1B engine that will exclusively power the Boeing 737 MAX. CFM ran the engine for the first time on June 13, three days ahead of schedule. The LEAP-1B engine, installed in a test cell at Snecma (Safran) facilities in Villaroche, France, successfully completed a series of break-in runs before reaching full take-off thrust.

The engine will be on test for the next several weeks, during which time CFM will verify its mechanical operation, operability (stall margin), engine starts and further validate the advanced technologies incorporated in the engine, including the woven carbon fiber composite fan, the Twin-Annular, Pre-Mixing Swirler (TAPS) combustor, ceramic matrix composite shrouds in the high-pressure turbine and the titanium aluminide blades in the low-pressure turbine. The LEAP-1B is specifically optimized for the 737 MAX with a smaller, highly efficient core and benefits from these new technologies.

According to Cédric Goubet, Executive Vice President for CFM, "All of the testing we have done to date has validated the technology choices we made."

The LEAP-1B engine is expected to contributs significantly to the 737 MAX's fuel efficiency improvement. The 737 MAX will be 14% more fuel efficient than today's most efficient Next-Generation 737s–and 20% better than the original Next-Generation 737s when they first entered service.

Boeing claims that "the 737 is more fuel efficient than the A320 today and will be more fuel efficient than the A320neo tomorrow. Airlines operating the 737 MAX will see an 8% operating cost per seat advantage over the A320neo."

CFM was on track to deliver the 10,000th CFM56-7B engine for the Next-Generation 737 by the end of June, making it the best selling engine-airframe combination in history.