CFM International will not decide on increased production of its Leap programme until a delay in its existing ramp-up plan has been made up, as is targeted for later this year.

Leap production fell behind schedule earlier this year because suppliers of a "very small number" of parts – in particular castings and forgings – did not meet production targets, executive vice-president and general manager Sebastien Imbourg said during a briefing in London on 14 July, ahead of the Farnborough air show.

Imbourg says this was not a matter of part design or technology, but a "first-time yield issue": the proportion of components that had to be scrapped because they did not meet production standards was too high.

Recovery plans have been implemented, and CFM is "now delivering at the rate we have to", Imbourg says. But he notes that production needed to be raised as a result of the delay, in order to keep pace with scheduled increases in the ramp-up plan.

The delay in CFM's Leap delivery plan peaked at around seven weeks and has since been reduced. "We are confident we will close the gap in 2018," Imbourg says.

While CFM has a dual-source policy, this has been increased to four suppliers for certain parts.

Over the full course of this year, CFM intends to deliver, for the first time, more Leap than CFM56 engines – at least 1,100 versus 1,050, respectively. "But we are just in the middle [of the ramp-up plan]," Imbourg says. More than 2,000 Leap deliveries are foreseen for 2020.

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Airbus and Boeing are evaluating further increases in their respective A320-family and 737 production rates, but Imbourg says CFM's priority is to restore its existing ramp-up plan. He says CFM will decide in 2019 whether it can raise production further.

The Leap-1B is the sole powerplant available for the 737 Max, while the -1A competes with Pratt & Whitney's PW1100G geared turbofan on the A320neo family.

Both the Leap-1A and -1B have been affected by a premature loss of a barrier coating on high-pressure turbine shrouds made from ceramic matrix composites.

Executive vice-president and general manager Allen Paxson says "the shroud is fine", but the coating loss cuts exhaust gas temperature (EGT) margin and, as a result, reduces time on wing before engines require restoration.

He says CFM has been able to recertificate the engine with increased EGT margin – to boost time on wing – because the engine was tested under harsher conditions than required for the original certification.

Additionally, CFM introduced in June a modified shroud with a thinner, more durable barrier coating. Paxson says the improvements were achieved through process changes rather than reformulation of the coating.

He acknowledges that in-service engines with the original coating reached EGT margin limits. But he says the issue could be resolved through scheduled quick-turn shop visits focused on restoring the shrouds, and that affected airlines were provided with spare engines to avoid operational disruption.

Source: Flight Daily News