Airbus at thirty - Stretching the very limits

Airbus is throwing down the gauntlet with the latest record-breaking arrival in the A340 family, the -500/-600 models

Julian Moxon/TOULOUSE

Even seasoned onlookers caught their breath when the newest Airbus emerged from the Clement Ader factory in Toulouse on 20 September. The A340-600 is the longest commercial aircraft ever built - and, with the four Rolls-Royce Trent 500 engines still to be attached at that time, it looked every millimetre of its 74.8m (245ft) overall length.

The 380-seat A340-600 is the first of the two stretched, re-engined variants of the original A340-300 which entered service in March 1993. By Airbus standards to date, the -600 is a monster and is the first product from the consortium which - in terms of seating capacity - competes directly with the Boeing 747. Only the A380 will be larger. When it enters service in early 2006, it will take Airbus beyond the 747 into a totally new marketing domain.

In terms of development, first flight and delivery, the -600 leads its smaller, longer-range sister, the 313-seat A340-500, by about seven months. The first of 10 -600s ordered by Virgin Atlantic is due for delivery in June 2002, and the first of five -500s will go to Air Canada in November 2002.

Orders for the two aircraft stand at 71, from 10 customers, with a further 53 commitments. While business was slow in 2000 with just eight orders booked, A330/A340 family product manager Alan Pardoe remains bullish about the prospects for the pair, which he says offer "new standards of comfort and flexibility for passengers".

For Emirates managing director Maurice Flanegan, the arrival of the A340-500 opens up new possibilities: "With this aircraft, we're going global," he says. "No other aircraft has its range, and we intend to take full advantage of that." Flying to New York in the first instance, the -500 will be operated to South America and Australia, and on "any routes where it makes money", he says.

While the two new types earn plenty of superlatives, Airbus Industrie is perhaps more focused on what the aircraft will do for its standing in the high-capacity long-range market, where competition with Boeing has become tougher after the launch of the 777-200LR/300ER last February.

While only 13 passenger 747s were sold last year (including the launch order for six -400Xs from Qantas), orders for 777 variants have been strong, with a total of 107 for all types last year and 49 for the -200LR/-300ER. This increased pressure on the European manufacturer.

Development activity at Toulouse is intense as the first of three flight-test A340-600s is undergoing systems testing before its scheduled May first flight, and assembly of the first -500 gathers momentum. The fourth Rolls-Royce Trent 500 turbofan, rated at 56,000lb-thrust (249kN), was mounted to the -600 wing on 15 November following completion of the first phase of flight testing on the inboard left pylon of an A340-300 testbed aircraft on 20 August.

During the 47h, 34-flight programme, the engine's overall performance was found to be "very encouraging", says Pardoe. "The Trent has demonstrated excellent operability. The overall behaviour of engine and nacelle is much better than it has been for other powerplants at this stage."

The Trent's arrival aboard the A340 signals the end of a long hunt for more powerful A340 engines that in 1986 led to International Aero Engines proposing the "SuperFan" - a geared fan development of the A320's IAE V2500 - for a new version of the aircraft. The attempt proved over-ambitious, however, and the project was abandoned.

Although the 34,000lb-thrust CFM International CFM56-5C engines powering the original A340-300 have proven reliable and adequate to the task, there is little doubt that the Trent will provide a huge power boost that will please pilots and air traffic controllers alike.

The overriding aim throughout theA340-500/600 development programme is to achieve a mature product at entry into service, an example of which was seen in the completion of initial Trent 500 testing seven months ahead of the -600's first flight. Twelve "key maturity subjects" have been targeted, says Pardoe, "which take into account all airline experience to date, and which extend right down to equipment level".

Beside the obvious mechanical areas such as powerplant, landing gear and fuel system, these include, for example, the onboard built-in test equipment (BITE) maintenance diagnostics system, which Pardoe says "must be fully operational from the first flight".

Maturity preparation extends to cabin systems, testing of which will include passenger simulations during test flights to be carried out six months before certification, and route proving on long-range flights with a full passenger load: "We're even building a full-scale water and waste system mock-up," says Pardoe.

Critical aircraft systems such as the hydraulics, air conditioning and fuel systems will be tested both for operational limits and to ascertain their breaking point. A digital mock-up of the aircraft will be used to define procedures well before service entry.

Principal changes to the new A340s compared to their -300 predecessor include: a 10.9m fuselage stretch for the -600 and 3.2m for the -500; a 20% larger wing achieved by wing-box insert and extensions to the wingtips; increased fuel-tank volume (38% for the -600, 52% for the -500); a new, larger horizontal stabiliser; a 0.5m height reduction for the A330-200 fin and rudder, and a totally new four-wheel bogie centre landing gear, with braking.

The cabin internal space has been thoroughly restyled and includes extensive use of light-emitting diode (LED)lighting, which provides far greater flexibility in the way illumination is distributed and has a bulb lifetime "longer than that of the aircraft". A new touch-screen flight attendant panel has also been developed which permits the display and control of far more information than before, including, for example, cabin temperature data.

Passengers will also benefit from the introduction of larger overhead bins designed to take the new roll-on bags that have become popular as carry-on luggage.

Airlines will be able to configure the lower deck in a number of ways by using container-sized roll-on/roll-off modules developed by Airbus. Crew rest compartments, extra toilets and lower-deck galleys or combinations of these will be accessible from a rear stair: "We've tried to modularise the design to provide a lot of solutions based around a common concept," says Pardoe. "We've already sold both full and partial bulk crew rest options."

He admits, however, that it has taken a "lot of clever design" to find the right balance between providing flexibility for passengers and cargo. "The market says freight is vital," he adds.

Performance estimates to date indicate that nominal design objectives should be met. For the -500, this is for a 15,725km (8,500nm) range with 313 passengers, and for the -600, 13,875km with 380 passengers, flying at a windtunnel proven Mach 0.83.

Initial structural and performance testing indicates that the -500 will be capable of a 3t higher maximum take-off weight and the -600 a 4t increase. This will allow either greater range or payload, giving the -600 the potential to reach New York from Dubai, prompting Emirates to consider converting three of its -500 options to the larger aircraft.

Airbus has been embroiled in a long-running discussion with certification authorities to try to have the A340-600 approved with six rather than eight passenger doors. The consortium had hoped to eliminate the two overwing hatches, required under European Joint Aviation Authorities and US Federal Aviation Administration rules, which specify a maximum distance of "60ft" (18.3m) between adjacent passenger exits. Pardoe says that although the "long-term debate is continuing" over the exit requirements, "it is clear that all currently ordered and in-build -600s will have the [additional] exits". The prototype -600, which does not have the exits, will be retained by the manufacturer as a testbed.

The consortium argues that not including the smaller overwing hatches would lead to improved safety because they could become blocked during an evacuation. Eliminating them would also save 500kg (1,100lb) in weight, provide room for an extra row of seats and reduce production costs by enabling the centre-fuselage design of the -600 and the shorter, longer-range -500 model to be standardised.

Airbus sees the A340-500/600 programme as a stepping stone to the A380 in terms of cabin comfort, systems reliability and advanced design. Launched in December 1997, 10 years after the launch of the A330/A340, the pair cost $2.9 billion to develop as against $3.5 billion (today's prices) for the first versions of the A330/A340.

This reflects both the greater standardisation of the new aircraft as well as improvements in design efficiency resulting from the introduction throughout the Airbus partners of the CADDS-5 three-dimensional design system.

But it also resulted in problems for one partner. BAE Systems suffered delays to wing production because some of its suppliers were not equipped with CADDS-5. The knock-on effect has meant a three-month delay to both programmes and consequent late delivery to the airlines. "We have kept them informed throughout," says Pardoe.

Virgin Atlantic will therefore receive its first -600 in June 2002 instead of March, while the first -500 will arrive at Air Canada in November 2002, instead of September.

Airbus will deliver 16 instead of 21 aircraft next year, with the last three delivered on time. The remaining five aircraft, all -500s, will be delivered in early 2003. "We will recover back to the contractual dates by early 2003," says Pardoe, adding that no sales have been lost because of the delay.

Flight testing of the A340-500/600 involves three aircraft in an 1,800h programme. The first, which will remain in Airbus' inventory of flight test aircraft, will undergo general aircraft development, flight envelope and other certification testing. The second will carry out powerplant-related certification trials and the third will perform cabin systems, long-haul and route-proving tests.

A single A340-500 is due to undergo a further 500h of certification and feature tests.

Source: Flight International