CFM International is poised to roll out a series of upgrades for its Leap narowbody engine family designed to address operational and durablity issues with the powerplant.

As of 31 May there were 2,713 Leap-powered aircraft in service – 1,504 Airbus A320neos, 1,208 Boeing 737 Max jets, and a solitary Comac C919 – which are demonstrating a flown-days ratio of 92%, says the GE Aerospace-Safran joint venture.


Source: Airbus

High-pressure turbine improvements will address durability issues

Although the engine is generally demonstrating high levels of reliability, and is showing greater maturity than the preceding CFM56 at the equivalent point in the programme, “there are some components we are addressing based on customer feedback”, says Karl Sheldon, CFM executive vice-president.

Most prominently, CFM is changing the design of blades and nozzles in the high-pressure turbine to address durability issues experienced by operators in harsh environments such as the Middle East.

“The durability of the core is not where we expected it to be,” said Sheldon briefing journalists in Paris on 17 June.

Those upgraded components are now undergoing a rigorous testing regime, including dust ingestion, to “replicate what we are seeing in the fleet”, he says.

“We are proving to ourselves that the blade will do what we expect it do.”

CFM expects to introduce the enhancement to new-build and in-service engines “from the latter half of next year”, adds Sheldon.

LEAP_Dust_Ingestion-0091 (1)

Source: CFM International

CFM has been performing dust-ingestion tests with Leap-1A engine in Evendale

Additionally, from later this year, CFM will implement a change to the starter air valve on the Leap-1A to improve reliability, which Sheldon describes as a “pain point with some of our customers”.

“That valve sits on the fan case and is in a high-vibratory environment. We are working with our supplier to field a new design that will be isolated from the vibration.”

It will also address an issue with wear in one bearing housing, eliminating the resulting non-synchronous vibration.

Lastly, next year it will also deal with a fuel nozzle coking problem through the introduction of what it calls the “reverse bleed system” which improves cooling of the components after shutdown. The retrofitable solution, will “alleviate a maintenance burden associated with fuel nozzle changes”, says Sheldon.

However, he stresses that overall the Leap is exceeding the manufacturer’s expectations. “It’s a durable, reliable architecture – we have no plans to do any major surgery.”