MAX KINGSLEY-JONES / LONDON
The ultra-long-range Airbus A340-500 is emerging from the shadow of its larger sibling, the A340-600, as the European manufacturer prepares the airliner for deliveries to launch customers
While the Airbus A340-600 has been making the news during the past 12 months as the latest and largest member of the European manufacturer's airliner family, its smaller, ultra-long-range sister, the A340-500, has been quietly undergoing its flight-test programme.
With the 380-seat -600 about to enter service with launch customer Virgin Atlantic on transatlantic services from London Heathrow, Airbus is now focused on completing certification of the smaller -500 ahead of deliveries at the end of the year to launch customer Air Canada.
While the -600 is the world's longest airliner, beating the previous record holder, the Boeing 777-300, by a mere 1.4m (4.6ft), the -500's range of 16,000km (8,650nm) gives it the longest legs of any airliner flying. Boeing is threatening to steal this crown with its planned -200LR derivative of the 777, which can fly 16,400km, but this will not happen until at least mid-2005, as the programme has been delayed.
Airbus says that its goal is to capture at least half of the 1,500 sales that are forecast for the ultra-long-range category over the next 15-20 years, but orders have been sluggish since the flurry of deals in 1997/98 after launch. The -600 is the more popular model, which is why it has been in the vanguard of the development programme and the recipient of 49 orders. There have been 19 firm sales of the -500 to four customers - Air Canada has ordered two aircraft, Emirates six, International Lease Finance is to acquire six and Singapore International Airlines (SIA) has ordered five.
Director of product marketing for the A330/A340 family Alan Pardoe says: "Since we launched, Boeing has come along with the 777 'X models' [-200LR/300ER], so there has been something else for the market to look at. I don't think the market will make up its mind [about the -500] until it sees it flying passengers. Airlines are still to decide on the benefits of ultra-long range."
Focus groups
Pardoe says the -500 "invented itself". He says that after Airbus decided the growth variant of the 295-seat -300 should be a 20-frame stretch, the -600, "airlines in the early focus groups asked: 'why not use all that latent energy to go ultra-long range?'."
The A340-500/600 family has cost Airbus around $2.9 billion to develop. The backbone of the airliners' capabilities is the marriage of a new enlarged wing with the 53,000-56,000lb-thrust (236-249kN) Rolls-Royce Trent 500. The A340-500 emerged as a 313-seat aircraft (three-class), with a design range 20% greater than that of the -300 model and 2,310km longer than its larger sister, the -600. Pardoe points out that "after 7,500nm, there are few city pairs less than 8,500nm apart".
Longer and bigger
Compared with the A340-300, the -500 has a one-frame extension forward of the wing and two aft (to balance the enlarged wing). Combined with the three-frame wing-box extension, these increase the overall length to 67.9m. The -600's 20- frame extension comprises 11 forward of the wing, six aft and the three-frame wing-box extension (for a full technical description of the -600, see Flight International, 12-18 June, 2001).
Developed by Airbus UK, the new wing is 20% bigger than that of the earlier A330/A340 models, providing 38% greater fuel capacity (53,400 litres/14,090USgal) and 40% more lifting ability. The increase in area is achieved through the introduction of a tapered insert and three-frame wing-box extension, along with 1.6m wingtip extensions and the established 2m-span canted winglets.
Unlike the -600, the -500 incorporates an additional 20,000 litre centre-section fuel tank (item F16 on cutaway), increasing its fuel capacity compared with the -300 by a massive 50%, to 214,800 litres.
The A340-500 is powered by the baseline Trent 553 rated at 53,000lb thrust, while the -600 has the more powerful Trent 556 rated at 56,000lb. Chief engineer long-range programme Gordon McConnell says: "The engine is certificated at 60,000lb-thrust, so there is plenty of margin for growth. The -500's benchmark mission is SIA's Los Angeles-Singapore route, which is a 17-18h sector," says Pardoe. "This performance enables transpacific flights from South-East Asia to eliminate a technical stop at Tokyo."
Emirates will use the -500's range to operate year-round direct services from its Dubai hub to Los Angeles and New York. Airbus says other potential A340-500 missions include from the US Midwest to Australia, US East Coast to China or southern Africa, and southern Africa to Australia.
Both variants were originally offered with a baseline maximum take-off weight (MTOW) of 365,000kg (803,000lb) - at that time 90,000kg heavier than the heaviest -300. But, during production, Airbus established that the structure could allow the weight to be increased by 3,000kg to 368,000kg. "This has allowed us to offer -500 customers 150nm [280km] more range than the 8,500nm originally specified," says McConnell.
Other maximum weights have been increased in parallel, with zero fuel and structural payload both up by 2,400kg, to 225,000kg and 56,500kg respectively, while landing weight has been increased by 4,000kg to 240,000kg.
Much effort has been made in the production of the new family to reduce the empty weight with, for example, titanium used in the landing gear and engine mounting pylons. However, the early A340-500/600s have weighed in heavier than the target, with the deficit believed to be around 850kg. This is largely thought to be associated with the aircraft's wing.
Weight savings
"We'll be back on our specification target with aircraft delivered next year," says McConnell, who adds that a weight- saving programme is expected to bring the new A340 models within 0.4% of the originally specified empty weight by aircraft number 23. This is believed to be the first A340-500 for SIA.
The weight-saving effort, which Airbus UK's Filton plant is masterminding with input from its new US office in Wichita, Kansas, is understood to be focused on reducing material used in various stringers and ribs in the wing, as well as by removing material from some of the larger forgings within the structure.
Other key changes on the new family (see changes diagram on P42) include a revised fin and horizontal stabiliser to cater for the increased engine thrust, and new strengthened landing gear with an all-new four-bogie Messier-Dowty centre landing gear, incorporating its own braking system (this replaces the twin-wheel unit on earlier A340s). For the -500, Airbus has also done away with the overwing enlarged Type III emergency exit needed on the -600 to comply with the US Federal Aviation Administration's "60ft rule" which dictates the maximum distance between exits.
The A340-500/600 both incorporate Airbus's standard fly-by-wire glass cockpit and sidestick controls and are approved for single type-rating with earlier A340 models. They are the first to be equipped with Thales-supplied active matrix liquid-crystal displays which will gradually become standard on the other models.
Airbus has heavily revised the A340's passenger cabin and is redeploying the changes into established A330/A340 models as part of the Enhanced programme. The main cabin area has been thoroughly restyled and includes new overhead bins. Light emitting diode (LED) lighting replaces halogen bulbs and provides much greater flexibility in the way illumination is distributed.
A new touch-screen flight-attendant panel has been developed to allow the display and control of more data than before, and enable cabin crew greater choice in choosing lighting colours and dimming combinations.
The -500's direct competitor is the -200LR derivative of Boeing's 777 twinjet, which has a tentative mid-2005in-service target. Boeing has just one customer - EVA Airways - for the 777-200LR. Last year the US manufacturer put the aircraft's development on ice, pending an improvement in trading conditions. A second competitor has recently emerged in the form of a 747-400X derivative equipped with a spacious 250-seat cabin offering a range of around 15,800km.
Airbus claims several benefits over the -200LR. An A340 operator has "four-engine freedom", not having to be concerned with extended-range twin-engined operations regulations that apply to the 777. The A340's nine additional seats are worth $9 million annually, says the manufacturer, while direct operating costs are around $900,000 less per year.
Airbus also says four Trent 500s are 10-12% cheaper to maintain in engine direct maintenance cost (DMC) terms than the two General Electric GE90-110/115Bs powering the new 777 models. The -500'soverall DMC (airframe, engines and nacelles) is 7% lower than for the 777-200LR,according to Airbus.
Software delay
Flight-testing of the A340-600 began in April last year, around four months later than planned, due to a delay in the installation of new design software at suppliers to BAE Systems. The new model was awarded European Joint Aviation Authorities certification on 29 May, following completion of its 1,600h test programme.
Deliveries of the new airliner family kicked off this month, with the handing over to Virgin of the first of 10 -600s. Initial A340-600 deliveries are running around three to four months behind the original schedule as a result of delays to the first flight. This has had a similar effect on the-500's schedule.
Virgin's initial -600 services will be between London Heathrow and New York Kennedy. Airbus has put specific measures in place to ensure that Virgin's initial A340-600 flights go as smoothly as possible. There will be increased support from Airbus and its main vendors at key airports in the airline's network. In-service data will be tracked and analysed to anticipate potential issues and dedicated teams will be in place at Airbus facilities to ensure minimum reaction time to any problems.
The first A340-500 flew on 11 February and this aircraft is completing the bulk of the 350h flight-test programme. The high level of commonality between the two models means much of the data from the-600's trials are applicable to the -500. Towards the end of the -500's test programme, the first customer aircraft (for Air Canada) will be used for a small amount of testing of the passenger cabin's systems, such as air conditioning distribution and the new lower-deck crew-rest area.
Predicted performance
By the beginning of this month, the A340-500 prototype had flown over 240h and more than 74 flights. Take-off, cruise and climb performance evaluation, flutter and stall tests, and minimum control speed take-off trials had all been completed. The full flight envelope - 41,000ft ceiling and 330kt (610km/h)/M0.86 maximum operating speed/Mach number - has been explored.
The aircraft is now being used to fine-tune handling qualities and control laws for the fly-by-wire system, and to test autopilot, fuel and air systems. Airbus says results show take-off, climb and cruise performance to be as predicted or better.
During performance testing of the larger A340-600, it emerged that climb to initial cruise altitude performance at MTOW was "significantly better" than the target of 33,000ft, says McConnell. The -500 is exhibiting similar performance gains, he adds. "The -600 can reach 35,000ft in under 30min," says McConnell. This was against a target time of around 38min. He adds that the buffet boundary has also turned out better than predicted at all Mach numbers.
"The new wing has much better lifting capability than predicted," says Pardoe. "The whole performance during the take-off to top-of-climb regime is better - it can lift 6t more payload than we expected."
The wing's tapered insert provides slightly greater wing sweep, up from 30¡ to 31.5¡, and greater chord, without any significant increase in depth, yielding a small boost in cruise speed. Airbus says the aircraft will cruise "close to M0.83" compared to the earlier wing's M0.82 design cruise speed.
Airbus has rerun its rejected take-off certification tests for the -600, after many of the wheels suffered structural failure during the original test in February, when tyre pressure rose dramatically because of brake heat. The wheels and tyres have been redesigned and a second test was completed successfully in May. The A340-500 is due to receive FAA and JAA type certification at the end of October, with deliveries beginning the following month to Air Canada, which is expected to put the new aircraft into service by the end of the year on Toronto-Hong Kong services.
Airbus expects to deliver 11 A340-500/600s this year and 27 in each of the following two years. When it has finished its testing work in November, the prototype -500 will be refurbished for delivery to Emirates in 2003.
Despite the outstanding payload/range performance of the new family, Airbus is already feeling the pressure for more-capable variants. Emirates wants to supplement its A340-500 fleet with a heavier extended-range version of the -600 to enable it to fly year-round from Dubai to the USA. The airline holds a letter of intent for eight aircraft, pending a decision by Airbus to go ahead with the airliner. Boeing is threatening to push the -500 with its planned 777-200LR which, in theory at least, has the greater range capability.
Spare thrust
Airbus is reluctant to divulge details of weight-growth plans it has for the new family. "When the certification programme is wrapped up, our process is to consolidate all the data to see if there is structural capability to exploit," says McConnell. "With the Trent 500 certificated at 60,000lb thrust [4,000lb above the -500/600's current requirements], there is plenty of thrust in hand for any future developments."
Source: Flight International
