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CFM reviews fleet after finding Leap-1A durability issue

CFM International is evaluating the Leap-1A engine fleet on Airbus A320neo aircraft for a prematurely-deteriorating coating on a turbine part after identifying the problem on eight engines in service.

The scope of the problem should be understood within two weeks, says a GE Aviation spokesman. GE and Safran are equal partners in the CFM joint venture, but GE is responsible for the high-pressure turbine module.

As the fleet-wide review continues, GE plans to validate a new adhesion process for the coating to insert into the production process in early 2018, the spokesman says.

The discovery means Pratt & Whitney isn’t the only engine supplier facing a potential fleet-wide durability problem shortly after entry into service. CFM’s Leap-1A and P&W’s PW1100G compete for orders on the A320neo, with CFM holding a slight edge to date.

The first PW1100G-powered A320neo entered service in January 2016, but has been plagued with two parts with premature wear-and-tear. P&W has rolled out a durability fix for an oil seal in the No. 3 bearing. An improved combustor liner is scheduled to be certificated by the end of the year. But P&W parent United Technologies disclosed last week that the company is looking at “design alternatives” to further improve durability.

By comparison, the Leap-1A has enjoyed a relatively smooth entry into service since August 2016. It was not affected by a batch of flawed metal discovered last May in a few dozen Leap-1B engines powering the Boeing 737 Max.

CFM has delivered 97 pairs of engines to power A320neo and A321neo aircraft delivered to customers over the last 15 months, Flight Fleets Analyzer shows.

The durability issue was noticed in early October by a flight crew that a noticed a shift in the exhaust gas temperature margin during a flight, a GE spokesman. A borescope inspection revealed the coating of a ceramic matrix composite (CMC) shroud in the high-pressure turbine had started flaking off. The voids in the coating create a tiny gap for airflow passing through the turbine stage to escape.

GE introduced CMC’s for the first time in the high-pressure turbine shrouds and combustor liners in the Leap-1 engine. As the product of more than 25 years of research, the CMCs replace metal parts with a material that need less cooling air to prevent melting when exposed to exhaust gas from the combustor.

Although the coating is being replaced, GE’s spokesman emphasises that the CMC material itself is performing as expected.

CFM also has a global maintenance, repair and overhaul infrastructure available to retrofit engines with a new CMC coating, if a fleet-wide replacement is needed, GE says.

Safran has estimated the costs of transitioning from the CFM56 to the Leap engine will be up €400 million ($465 million), of which majority represents the difference in production costs, chief executive Philippe Petitcolin said 27 October on an earnings call.

(CORRECTION: The article is updated to make it clear the Safran estimate covers all contingencies and costs during the transition, not just the new durabilty issue.)

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