A320NEO

That basic design soon spawned a ‘family’ of variants – the A318, A319, A320 and A321 – where a common design philosophy combined with fly-by-wire allowed flightcrews to move between types with a minimum of effort by means of shorter cross-crew qualification courses rather than extensive ground schools and simulator training. For pilots this was a reprieve and for airlines it was cost-effective.

These innovations proved so popular that by the end of September 2016, Airbus held orders for more than 12,700 A320 Family aircraft. The new challenge was to build upon this solid foundation so that the A320 and its kin could continue to meet the needs of its airline customers as they called for enhanced efficiency. The answers were to be found in the two key elements of flight – the powerplant and the wing. And the neo was born.

The next step

The A320neo (new engine option) offers two of the latest-generation engine choices – CFM International’s LEAP-1A and the PurePower PW1100G-JM geared turbofan from Pratt & Whitney. Fitted to the A320 airframe, both engine types share the same fuel burn and handle identically.

The new engine choices when combined with the aerodynamic improvements sees the neo offer a 15 per cent fuel burn saving over the ‘current engine option’, or A320ceo. In an aircraft that typically burns between 2,200kg and 2,400kg per hour (depending on seating configuration), that’s a saving of up to 360kg per hour.

Furthermore, Airbus predicts that through further engine efficiencies, the fuel burn will be reduced by a further five per cent per seat overall by 2020. That is a significant reduction in cost across an airline’s fleet, hour after hour.

Originally equipped with ‘wingtip fences’ as their standard aerodynamic device, the A320ceo family has introduced a new blended winglet, or ‘Sharklet’, in recent years. Standing 2. 4 metres tall, these winglets have also been offered as a retrofit and considering that they offered the A320ceo an additional 100 miles of range, or 450kg of payload, their efficiency is tangible. The Sharklets are standard on the neo, although they are slightly different to the retrofitted winglets. Additionally, while the configuration with full landing flap, or ‘CONFIG FULL’, for the A320 remains identical for the neo, the configuration has changed for the A321neo when compared to its predecessor.

The neo airframe offers efficiency improvements in other ways too. It is equipped with a new electrical bleed system which saves weight and improves reliability. The undercarriage overhaul schedule has increased from 10 to 12 years, reducing maintenance costs, while the overall maintenance program directives, or MPD, provide a further five per cent saving.

Environmentally, the neo is quieter, at 19 decibels below the ICAO Chapter 4 standards. It has reduced its CO2 emissions by 15 per cent, or five tonnes per year per aircraft, while its nitrogen oxides, or NOx, are half of the current required standard. The neo’s engines are successful in both generating more power while producing lower amounts of the less desirable products.

Even within the cabin, clever use of space and even galley and lavatory layouts are facilitating additional seating. Airbus has also opened up innovative options in configuring the floor space and exit doors for the longest-fuselage A321neo version. This allows more flexibility and combined with higher exit limits, the A321neo’s maximum seating capacity will increase to 240.

On the flightdeck, the pilot interface remains the same between the ceo and neo, allowing the same streamlined training philosophy to exist. However, there are some changes beneath the surface. The neo offers greater rudder deflection with a consequent reduction in velocity minimum control (Vmc) and velocity minimum control ground (Vmcg). Broadly speaking, these are critical minimum speeds at which the pilot retains enough rudder authority to keep the aircraft continuing straight ahead both on its ground roll and in the air should an engine fail.

There is also a new electrical tail bumper system that utilises fly-by-wire to protect the aircraft against a tail-strike on the runway. That being said, the system still permits the pilot to apply full authority to ‘unstick’ the aircraft from the runway and ‘drag the tail’ should some unforeseen emergency situation require it.

The neo can also be fitted with an automatic traffic alert and collision avoidance system (TCAS) as found on its big brother the A380. The new AP/FD TCAS mode essentially completes the existing TCAS functionality by implementing a TCAS vertical guidance feature into the auto flight computer. The result is that now the auto flight computer can control the vertical speed of the aircraft which is adapted to each resolution advisory acquired from TCAS.

As a consequence, when a TCAS ‘resolution advisory’ (RA) is received, the pilot no longer needs to disengage the autopilot or flight director before conducting the TCAS manoeuvres. Rather, the autopilot can now automatically conduct the correct TCAS manoeuvre, to position the aircraft clear of any potential traffic conflict. Additionally, if the pilot is ‘hand flying’, there is no longer a need to turn off the flight directors as the new system provides flight director guidance in accordance with the TCAS resolution.

From powerplants and aerodynamics to maintenance and the flightdeck, it would seem that every aspect of the A320 has been closely examined in the development of the neo.

Taking flight

Computer models can make predictions, but ultimately flight testing is needed to prove the theories and meet the standards of certification. Sandra Bour-Schaeffer is the head of single-aisle development flight tests at Airbus and offered an insight in to what was needed to make the neo a reality. Initially, both new powerplant options were flight tested on the A320neo to achieve primary certification, Bour-Schaeffer explains. Consequently, when fitted to the A321neo, extensive further testing of the engines was not required.

However, despite the many apparent similarities between the ceo and the neo, from first flight in September 2014 the program still involved 3,500 flight test hours and included 75 per cent of the flight testing that would be needed if the neo was an entirely new aircraft type. After a successful flight test campaign the first Pratt & Whitney-powered neo entered service with Lufthansa in January 2016 while the first CFM-powered neo joined Turkey’s Pegasus Airline six months later.

The largest member of the A320neo family is the A321LR (Long Range). While the A321neo will be fitted with the standard centre wing tank, while the LR will have the option of two additional tanks. This will give it an impressive range of 4,000nm which would seem very suitable for trans-Atlantic routes.

But the A321neo’s range potential won’t just be of use on the trans-Atlantic – it could see an Australian airline operating from Perth to Hong Kong or Shanghai, or Sydney to Tahiti.

The A321’s potential has been illustrated by the fact that of the 4,800 orders for the A320neo Family to date, more than 1,300 are for the A321neo.

Operators from across the Asia Pacific region have seen the potential offered by the neo and airlines ranging from Air Asia and Air New Zealand to Jetstar are just some of the 87 airlines that have ordered the neo family so far.

Airbus has a history of innovation, but in the case of the neo it is more a case of building upon a proven product. Now production of the neo has begun to ramp up, more airlines will soon experience the benefits that the incremental innovation this latest Airbus offers.

For Airbus and the A320 it is a neo chapter – as Aristotle once famously said, “The whole is greater than the sum of its parts”. And on considering the many enhancements that the neo has introduced to the A320 Family, this saying seems entirely appropriate.

The flight test program still involved 3,500 flight test hours.