Excitement About Engines!

The Commercial Jet Engine market has a vibrant future. In July, Boeing projected a global demand for 39,620 new airliners over the next 20 years, driven largely by the growth of low-cost carriers and emerging markets. Of these, 28,140 will be for new narrow-body planes such as the Airbus A320neo and the Boeing 737 MAX. Predictions of other agencies are equally bullish. And aircraft need engines.

Yet, profitability is another matter. With the prevailing cutthroat competition, engine manufacturers routinely offer heavy discounts on list prices to lure customers. New programmes are not half as frequent as they were in the last century. Indeed, advanced and often expensive technology comes into focus mainly when the price of oil spikes and the airlines become desperate to slash fuel costs. It often takes manufacturers many years to recover costs. For instance, US company Pratt & Whitney’s latest PurePower engine swallowed $10 billion in investment and took over 30 years to develop. That is why CFM International was content to enhance its iconic CFM56 engine to produce the Leading Edge Aviation Propulsion (LEAP). Variants of these two new engines seem set to dominate the commercial aviation scene for decades ahead.

Leaping Ahead

Think ‘jet engine’ and the first image that comes to mind is CFM International’s CFM56. CFM is a 50-50 joint venture between GE Aviation of the US and Safran Aircraft Engines ( formerly Snecma) of France. The CFM56 first entered service in 1982, but still notches up orders. In the words of Jean-Paul Ebanga, President and CEO of CFM International, “The CFM56 family has grown to be the best-selling engine in commercial aviation history. Not only is it the most produced engine, though, it has also proven to be the most reliable, as well as providing our customers with the lowest overall cost of operation in the industry; it is literally the gold standard for engines in this thrust class.” His claims are backed by statistics because the 30,000th CFM56 engine was delivered this year and there is a backlog of about 3,000. Production rates too are stunning 886 engines in the six months to June 30, 2016.

The CFM56 is now the exclusive power plant for the best-selling Boeing 737, and a popular choice on its fierce rival, the Airbus A320, which also offers the IAE V-2500 engine manufactured by International Aero Engines (IAE). The CFM56’s success hinges on innovation, high performance as well as continuous improvement over the years. It is also highly reliable and frugal in maintenance needs, with an average time on wing of 30,000 hours.

Given this imposing pedigree, it is but natural that the CFM56’s successor, the LEAP engine series, should have aroused intense customer interest even before it has proved its credentials. So far, CFM has delivered just a handful of these high bypass turbofan engines designed for next-generation jets. The LEAP-1A entered revenue service on August 2, 2016, when Turkish budget carrier Pegasus flew the first Airbus A320neo. While the LEAP-1B is on track for EIS in 2017 on the Boeing 737 MAX platform, the Chinese Comac C-919 powered by the LEAP-1C is due to fly for the first time by the year end.

What is so special about the LEAP that it should have attracted well over 11,000 orders till date? It makes extensive use of new materials and production technologies. It has an allcarbon fibre fan, made from a carbon-fibre hub and 18 3D woven carbon-fibre blades, which renders it lighter and more efficient. The high-power turbine employs ceramic matrix composites (CMC) – another technological first. Not only is this light, tough and heat-resistant material one-third the weight of metal but also it does not need to be air-cooled. The LEAP also features the proprietary Twin Annular Pre-mixing Swirling (TAPS II) combustor that helps slash Nitrous Oxide (NOx) emissions by half. CFM confidently claims this engine will deliver 15 per cent improvement in fuel efficiency compared to the CFM56.

PurePower Projection

Pratt & Whitney, on the other hand, has betted heavily on entirely new technology for its PurePower geared turbofan engine. In a nutshell, a geared turbofan includes a gearbox with the shaft, to let the compressor fan and low-pressure turbine each rotate at their most efficient speed. And the PurePower has a remarkably high bypass ratio of 12:1, meaning 12 times as much air flows around the engine core as the air that passes through it. This and other features reduce fuel consumption by 16 per cent compared to the A320ceo’s engine; noise levels by 75 per cent, CO₂ and nitrous oxide emissions by 60 per cent. In these days of mounting concern over global warming, it means annual carbon emissions reduction of about 3,600 tonnes per airliner. These claims have been borne out during initial operations.

The PW1100G-JM that powers the A320neo entered commercial service with Lufthansa on January 25, 2016. It is in service with at least four operators, and they have reported 99.8 per cent dispatch reliability. However, the engine also experienced teething troubles. For the technology minded, the main issue was “rotor bow” – slight thermal deformation and rotor-shaft misalignment caused by asymmetric cooling if the heat did not dissipate adequately between the previous engine shut down and subsequent start. More simply, it was taking too long to cool down before restarting, thus impacting the operations of carriers that try and pump in as many flights as possible each day.

Pratt & Whitney has been working feverishly to tackle this problem, as well as other issues like false alerts and claims to have succeeded. However, delivery schedule planned for Airbus A320neo has been significantly disrupted. For instance, IndiGo, the A320neo’s biggest customer with 430 planes on order, is slowing deliveries. Pratt will not be pleased by its reported intention to consider switching to LEAP-1A engines after taking delivery of 24 PurePower-equipped aircraft by March 2017.

AS OF FEBRUARY 2016, PUREPOWER HAD ATTRACTED OVER 7,000 ORDERS AND OPTIONS

Other PurePower variants are not affected and practically all the new sub-100-seat regional jets are counting on these high-technology engines to back their claims of double-digit performance improvements. The PW1500G powers Bombardier’s new CSeries narrow-body airliners that entered service with launch customer Swiss Global on July 15, 2016. The PW1900G will power the forthcoming Embraer E-Jet E2 family of which the E190-E2 made an early first flight on May 23, 2016. The PW1400G will power the Russian Irkut MC-21 airliner and the PW1200G will power the Japanese Mitsubishi Regional Jet. Both airliners are scheduled for EIS in 2018.

As of February 2016, PurePower had attracted over 7,000 orders and options. This is significantly fewer than LEAP orders but considering that PurePower is a new engine with yet unproven technology, it is an impressive tally.

However, the PW1400G may soon have a Russian rival – the Aviadvigatel PD-14, which is being offered as an option on the Irkut MC-21. Russia, which has largely been left behind in commercial turbofan technology, is now playing catch-up. The first flight of the PD-14 happened in 2015. This 8:1 bypass ratio engine promises to burn 10 to 15 per cent less fuel than the CFM56 and the V-2500 and claims to have 14 to 17 per cent lower operating costs.

Empowered Future

Glowing forecasts for airliners obviously translate into far higher figures for engines since each aircraft has at least two, while wide-body jets such as the Boeing 747 and the Airbus A380 (currently the world’s largest passenger airliner) need four power plants. Although engines are by far the most complex part of any aircraft and the most maintenance hungry, jet engines usually have a time between overhauls (TBO) of over 20,000 hours. There is also a flourishing engine maintenance, repair and overhaul (MRO) industry that thrives on making engines as good as new.

Large airliners, of course, need large engines such as the Rolls-Royce Trent XWB, the exclusive power plant for the Airbus A350 XWB. The Trent 7000 will power the forthcoming Airbus A330neo. It has a bypass ratio of 10:1 and improves specific fuel consumption by 12 per cent compared with the existing A330 engine apart from reducing noise levels by half.

The world’s largest engines come from US company General Electric. General Electric’s GE9X selected for the underdevelopment Boeing 777X airliner, is rated at 1,05,000 lb thrust. Its nacelle diameter is 178 inches or 30 inches more than the full fuselage cross-section of a Boeing 737. It is scheduled for certification in late 2018. But it is not the most powerful jet engine. That record is still held by General Electric’s GE90-115B which generates a gargantuan 1,15,000 lb of thrust and has powered the Boeing 777 since 1995.

On that super-powerful note, it’s time to end!