Manufacturers of large commercial aircraft engines are in the fortunate position of having order backlogs equating to years of production. But the steep ramp-ups required for new-generation engines – notably those powering narrowbodies – have put manufacturers and their suppliers under severe pressure.

Flight Fleets Analyzer indicates that GE Aviation-Safran joint venture CFM International has an order backlog of around 14,000 Leap engines, variously destined to power Airbus A320neo-family, Boeing 737 Max and Comac 919 jets; there are meanwhile more than 700 CFM56 engines still on order for 737NG and A320ceo-family jets. Given a current production rate of around 2,000 engines a year, the CFM backlog translates to seven years of production.

Pratt & Whitney seems to be in an especially privileged position in the regional jet segment as its PW1000G-series geared turbofan is the sole powerplant available for the A220, Embraer E-Jet E2-family and developmental Mitsubishi MRJ. The engine is also an option on the Irkut MC-21. However, the bulk of GTF orders are for the PW1100G, which powers the A320neo.

The GTF engine has been selected for around 26% of the A320neo's order backlog. For the entire PW1000G series, Flight Fleets Analyzer lists a backlog of around 4,800 engines.

GE has a backlog of around 2,700 engines – spanning the GE90, in-development GE9X, GEnx, CF6 and CF34 types – while Rolls-Royce has a Trent backlog of around 2,400, Flight Fleets Analyzer shows.

R-R says it intends to deliver around 600 Trent engines in 2018 – up from 483 last year – under a plan to ultimately double engine output. GE foresees a roughly 15% year-on-year rise in total deliveries in 2018, to about 4,000 engines, including those produced by CFM and for military customers.


But the story does not end there. P&W and R-R have received broad coverage for in-service issues on their respective PW1100G and Trent 1000 engines – the latter is an option on the 787 – which have caused disruption for airlines and airframers.

An eight-week delivery suspension of PW1100G-powered A320neos – lasting until April, and related to a flawed knife-edge seal in the high-pressure compressor – was the latest in a series of events that led to more than 100 newly assembled narrowbodies being parked at Airbus production lines earlier this year for lack of available engines.

This was not solely the result of problems with the GTF programme, however – and Airbus has not been the only manufacturer to park aircraft. Boeing in recent weeks has also been forced to store incomplete aircraft because of component shortages, especially of engines.

In January, CFM disclosed that Leap deliveries had fallen four to five weeks behind schedule owing to supply chain bottlenecks. That delay later increased to seven weeks before being reduced back to four to five weeks, said executive vice-president and general manager Sebastien Imbourg in July.

As part of a recovery plan, the manufacturer adopted a dual-source strategy for critical components, and further increased the number of suppliers for certain parts. But Imbourg acknowledges the particular challenges in catching up after a delay to a ramp-up programme.

The delay was caused not by design or technology problems, but by "first-time yield issues" with a "very small number" of parts, says Imbourg. Castings and forgings did not meet production standards, and scrap rates were higher than expected.

During a financial results call on 6 September, Safran chief executive Philippe Petitcolin said the production delay would be reduced to "almost zero" by year-end. Delivery delays have not been "aggravated" over the past two to three months, he says, but the manufacturer has still not caught up with issues encountered in the first half and, previously, in late 2017.

CFM is currently handing 12-14 engines per week to Airbus, which must rise to 16 by year-end, while shipments to Boeing are at 14 engines per week currently, with a target of 18-20. Petitcolin says: "From what I have in front of me, it is feasible and we are going to make it. It is never zero-risk – it is a challenge every day – but I have confidence we will achieve this goal. We need it."


It does not require many supplier issues to disrupt an engine assembly line, says PW1000G programme partner MTU Aero Engines. Speaking at the ILA Berlin air show in April, chief executive Reiner Winkler said problems at one or two "critical" suppliers are enough to cause delays – and some "extreme dependencies" apply to certain suppliers that provide parts for multiple if not all engine OEMs.

MTU programme chief Michael Schreyogg confirms that supplier capacity for castings and forgings is "somewhat limited" across the aerospace sector. He tells FlightGlobal, however, that opportunities do exist to broaden the supplier base.

Noting growth projections for the aviation industry, he says manufacturers outside the aerospace sector consider it highly attractive and are willing to make investments in technology and capacity in order to win long-term supply contracts.

Schreyogg says that early production planning, investment in facilities and staff, and co-operation with suppliers are the keys to avoiding delivery bottlenecks later on.

MTU's GTF production planning began when the engine was in development. Schreyogg says the German manufacturer needed to restructure its industrial base for the programme – and a separate contract to supply turbine centre frames for GE's GEnx engine – because not only was MTU's output set to quadruple to around 4,000 shipsets across the decade though 2020, but new engine technology demanded a change in manufacturing processes.

Much of conventional engine parts production was transferred from the company's Munich base to a new plant in Rzeszow, Poland, while the headquarters was rejigged for highly automated blisk production and engine assembly.

"The real challenge for management is to start early enough with investment decisions. You have to have, first of all, sufficient infrastructure," says Schreyogg.


He acknowledges the possibility of "pressure from shareholders and the market" if production facilities appear "oversized" initially and might not be fully utilised for some time. But that is something "you just have to resist", as "having enough time to develop stable production processes and stable supply chain circumstances is really key for success"

He notes: "You don't want to change [production processes and suppliers] in the middle of a ramp-up."

Production changes during the engine's development phase are "not a problem" if such moves are necessary to "manage and eliminate risk before the ramp-up", says Schreyogg, but he warns: "Changing during the ramp-up… will kill you."

He says MTU has made investments in its supply chain and worked closely with suppliers to ensure they have sufficient infrastructure in place. "You need to be deeply convinced that your partner can deliver the part in the right quality and volume," he says.

In addition to limited supply of castings and forgings, R-R says "increased demand on raw materials – and, in particular, powder metals – is causing a challenge". The UK manufacturer says blade availability is a "key challenge" and notes that increased maintenance activity as a result of the Trent 1000 in-service issues has "certainly... stretched our supply chain".

But notwithstanding the Trent 1000 situation, R-R insists it has taken "many steps" to reduce supply-chain pressures as "we have seen the potential for these challenges for some time".

Steps included: dual-sourcing; adding new partners to the supply chain; employing laser-welding techniques and exploring additive layer manufacturing for certain components to reduce reliance on a "very small number" of specialists for complex forgings; and using in-house component production capabilities.

Internal production capabilities diversify the supply chain, "help to reduce the cost of parts", and provide flexibility, R-R says. It adds that when blade demand was increased by efforts to deal with the Trent 1000 situation, the engine maker was "able to move production around within our owned capability, [thus] releasing our partners and suppliers to focus on ramping up their delivery of the most modern, complex parts".

GE says its "main production challenge" is "record demand for CFM engines overall, coupled with the speed of the Leap production ramp-up".

The joint venture's annual output has grown from around 1,600 CFM56s in 2015 to this year's targeted 2,100 engines, just over half of them Leap models. CFM delivered 77 Leap engines in 2016 – the year of the type's service entry – and 459 in 2017.

In 2018, the manufacturer intends to produce, for the first time, more Leap engines than CFM56s. For 2020, the plan is to deliver more than 2,000 Leaps a year, while CFM56 production will be wound down.

In addition to growing its supplier base, GE says it has established "intensive and continuous engagement with our suppliers at all levels" and set up "cross-functional teams to help identify and break production constraints". The US manufacturer also notes that it and Safran have in recent years expanded their manufacturing footprint and intensified efforts to introduce digital tools in order to raise engine output.

However, CFM's priority is to eliminate the delay in its existing ramp-up plan and stabilise production under current targets. The engine maker has repeatedly said it will not discuss with Airbus and Boeing potential further production increases before 2019.

Winkler similarly commented in April that the existing ramp-up plan was already "very steep" and that MTU had to stabilise the current situation before making further commitments. He described it as pointless to "prematurely agree objectives [on production increases] without knowing in detail what effect that will have on the supply chain".


Schreyogg acknowledges supply bottlenecks for castings and forgings across the aerospace sector, but thinks that for current-generation equipment the situation can be made "manageable" by stockpiling critical parts – to anticipate delivery fluctuations – and recruiting new suppliers.

For new technologies, including ceramic matrix composites, the situation is different, however. Schreyogg notes that CMC production facilities are located outside Europe today and argues that engine manufacturers and suppliers in the region must establish production capacity for new technologies before they can be employed on future programmes. "We really need to build up a European supply chain for such material," he says.

Central to that effort will be the planned joint development of a Future Combat Air System (FCAS) between France and Germany. Schreyogg notes that MTU's blisk technology for the GTF's high-pressure compressor is directly derived from the Eurofighter Typhoon-powering EuroJet EJ200 engine, for which the German manufacturer employed blisks for the first time on a serial production programme during the 1990s.

The planned Franco-German fighter will play a similar role maturing new technology that can be employed – on a large scale – on future commercial engines, in Schreyogg's view. He argues that "a prime reason" for governments to invest in FCAS is to establish manufacturing capabilities and capacity for future technologies so as not to be dependent on sources outside Europe.

"It is not just [about] the development of a fighter aircraft or fighter engine. But it is really also the development of a European-based supply chain to have, first of all, independence and, secondly, stable and secure access to such capacities and technologies."

Schreyogg adds: "Through a capable industrial set-up we can contribute to avoiding such industrial dependencies leading to political dependencies."

Source: Cirium Dashboard