Thursday, December 10, 2009

A-380 Two Years Into Service: A Report

A-380 Two Years Into Service: A Report

When the Airbus A380
entered service with Singapore Airlines in October 2007, it ushered in a new era for the world's airlines of the ultra-large airliner.For Airbus it was crucial that when the revolutionary aircraft made the headlines during its debut - as it inevitably would - it was not for the wrong reasons. After the programme suffered lengthy production delays that resulted in the assembly process having to be reinvented, there were sceptics waiting to see if the double-decker would fall on its face when it began earning money.
Two years on since that debut, the 20 A380s in service with three airlines - SIA, Emirates and Qantas - have accumulated 75,000h, operated 8,000 flights and carried at least 2.5 million passengers. Air France joins the throng this month. Flight International has spoken to all three early operators and the consensus is that the aircraft has delivered on its promise of heralding a revolution in passenger enjoyment and operating cost performance, but suffers niggling problems that have taken the shine off an otherwise outstanding entry into service.
"Despite a teeth-pulling two years through all the delays etc, this aeroplane is a peach," says Emirates Airline president Tim Clark. "Once you've flown on it you will not want to go [any other way] if you have a choice - which will make them feel very ill in Seattle."

All the operators echo Clark's view that the A380 has proved massively popular with passengers, evidenced by the fact that their fleets consistently fly at high load factors. But Clark points out that the downside of this is that "lose one, and you're in trouble".The operators put the A380's passenger appeal down to a combination of the quiet and spacious cabins, high standard of in-flight entertainment and the giant's comfortable ride. "She goes through turbulence like a huge Queen Mary 2 on the North Atlantic in January," says Clark.

While Emirates was not the first to receive the aircraft, it is the biggest customer, with an order for 58 Engine Alliance GP7200-powered aircraft. It received its first 489-seater in July 2008 - a date that like fellow customers was subject to a series of reschedulings that pushed back its first delivery by more than two years from the original plan agreed at the time of the order.

The carrier now has five A380s in service and 10 more (with capacity increased to 517 seats through the deletion of the maindeck crew rest compartment) are due to be delivered by the summer of next year. "After that we have dates that remain fluid," says Clark.

Nine months before the first Emirates delivery, it was SIA that led the way as launch operator, taking its first of 19 Rolls-Royce Trent 900-powered A380s on 15 October 2007 and putting the 471-seater into service 10 days later between Singapore and Sydney.
The airline had been due to receive its first A380 in the second quarter of 2006, but a six-month delay in certification was compounded by production woes that pushed first delivery back a further 10 months. This was largely due to the now infamous rewiring problems as Airbus struggled to get its head around the complexity of the cabin customisation process amid digital mock-up discrepancies.

"The first three months went almost flawlessly. We were breaking new ground everywhere. It was something everyone in SIA felt so proud of," says the airline's senior vice-president flight operations Capt Gerard Yeap.
Qantas took its first Trent 900-powered A380 in September 2008 and operates five aircraft in a 450-seat configuration. The airline's group executive operations Lyell Strambi describes its A380 experience as having been "exceptional, from both operational and customer perspectives. Expectations have been more than met."SIA flew a single-aircraft fleet on a daily rotation between Singapore and Sydney until January 2008, when its second A380 arrived.
That first airframe (MSN003) had a remarkable first two months without suffering a single technical delay or cancellation, says SIA senior vice-president engineering Mervyn Sirisena.

He concedes that the 10 months between certification and first deliveries gave all stakeholders breathing space to get on top of all the major issues. "When the aircraft was delayed we took the opportunity to work with Airbus and the OEMs to see what we could fix before service entry.
What we couldn't fix we made sure we understood and were prepared for," Sirisena says.He gives as an example the cartridges that deploy the slide rafts, which initially had to be replaced after only 70 flights until a redesign extended this interval substantially. With the A380 operating an intense daily rotation from the get-go, Sirisena says that the airline's marketing took a sympathetic view to scheduling. "They made a bit of a sacrifice by choosing a sub-optimal widow for the return leg from Sydney to give us enough time when the aircraft arrived in Singapore to fix defects and prep it for the next service.
"The aircraft would arrive at around 14:00 and was ready for the next service at 20:00. Every day we had a cut off at 18:00 when we had to declare service availability or not."None of the operators have any issues with Airbus's support for the new aircraft. Clark - who is a particularly hands-on airline boss from a technical operations perspective, says Airbus has "an army of people in Dubai, supporting us" and that he speaks "directly" to Airbus boss Tom Enders about issues.

Sirisena points out that with the A380 being a "showcase, there has always been a very strong support presence from Airbus, although it has been scaled back from the 'meet-and-greet' level when it first went into service".John Vincent, who was Qantas's acting executive manager engineering at the time of the interview, concurs on the airframer's contribution. "Airbus has provided, and continues to provide, a high level of support at all destination ports across our A380 network. Airbus specialists are on hand for all arrivals and departures and there is a substantial presence in Sydney, where the maintenance operation is based," he says.

"In conjunction with the various modification packages, Airbus and its suppliers continue to provide additional spare parts to facilitate parts update and upgrade. Technical data assistance has been of a high standard."Vincent gives as an example the help Airbus provided to Qantas with the commissioning of the electronic log book. "A specialist was located in Sydney for several months that had access to the design and support functions in Toulouse," he says.

Technical Issues
As the A380 in-service fleet has expanded, problems have come to light. To address known problems, as well as the in-service issues, the fleets are undergoing major modification programmes at timed intervals.

The first notable issue that SIA faced occurred around three months in, just after the second aircraft arrived, when a fault surfaced with the alternate brake system in Sydney. However, Sirisena says that "compared with the early days of the A340-300 or 777, the problems have not been that significant".Clark says that the Emirates fleet is undergoing "a big mod programme that requires removing an aircraft from service". This should be completed on the five delivered aircraft by February.
New aircraft it is due to receive will have the latest modification standard, he adds. Upgrades address issues with software, fuel line pressure sensors and body gear steering, among other things.
SIA now has 10 A380s - more than the number of passenger Boeing 747-400s it has in operation. Its A380 fleet's average daily utilisation is about 14h, while technical dispatch reliability (TDR) is "hovering around 97-98%", says Sirisena. While that number is "not too meaningful" due to the relatively small fleet size, he adds that it is "still very commendable" and is higher than the 747-400 was at the same stage of its development, although Sirisena points out that modern aircraft have a much-increased level of diagnostics available.
The industry's typical technical dispatch reliability benchmark is above 98.5%, and Clark says that while Airbus is guaranteeing 98.5% "we're not there yet. We're at 97%, sometimes 96%."The major problem being experienced is the plethora of system nuisance warnings, which are "driving down technical dispatch", he says.
"Airbus is very, very anxious to get the issues sorted out," Clark says.Emirates and SIA both perceive the A380's warning system as being too sensitive, resulting in misplaced fault messages about systems or equipment. "They didn't build enough tolerances into the software, they've made it overcomplex," says Clark. We have false alarms but we're not prepared to dispatch until they're sorted out."

Sirisena says: "What we are grappling with are algorithms for failure detection, which not only detects a failure but also acts upon it. Unfortunately this can lead to a perfectly healthy system being shut downor [a no-go fault warning] for a problem that was minor enough to have been deferred."Once we identify a problem and understand it, Airbus will quickly come up with a work-around. But it is not so straightforward to reprogram."

Clark says that the problem with the nuisance warnings has been their diverse nature, but "the common thread" is the software. He says Airbus executive vice-president programmes Tom Williams and his team "have sat in my office many times and said they can't identify trends, which is the worst possible thing".
Clark blames the software's design. "There was a philosophy of utopia - I suspect that Airbus was blessed with some boffins who said 'we've got to make this absolutely perfect - no flexibility'. The slightest surge causes one [sensor] to trip and then six more as they're all linked," he says."The engineering support teams - both Airbus and Emirates - have had to catch up on this complexity curve of the software. So there is a learning game going on.
I've told Airbus it needs an audit of the software on this aeroplane, and I've asked them how they're going to address it."Airbus has undertaken to raise Emirates' TDR to the 98.5% target by 31 December, but Clark is sceptical this can be achieved. "They've got some work to do," he says.Qantas is less specific about the problems it has suffered, with Vincent saying that while the airline "did encounter some issues" it "worked closely with Airbus at the time and these were resolved quickly".

Issues included a fuel tank indication system problem that affected two aircraft and a nose wheel steering issue on one, he says.

Airbus's Williams says that this latter problem was caused by water ingress into the rotary transducer on the gear leg that identifies its position. "The water was freezing on long flights, which was causing the sensor to give inaccurate positioning. There's been a design change and in the meantime an inspection procedure has been implemented."

Strambi says that the Qantas A380 fleet's dispatch reliability has been "good". A small number of technical issues had an impact on operations for a short period, but generally "we have been happy with the aircraft's reliability, considering this is the first 12 months of operating a brand-new fleet type".Clark says that while the Emirates fleet has also suffered some "hugely frustrating" failures of components, most are easily dealt with. However, one "pain" has been the repeated failure of the main gear steering system, which can force the aircraft to return to the stand as the steering is a minimum equipment list (MEL) item.
The trailing axle of the two six-wheel centre bogies is articulated to avoid tyre scrub on the inside wheels, and the wedge that must lock the steering in place for take-off has proved problematic, says Williams. "If the wedge doesn't position correctly then the crew gets a warning that requires a return to the gate. The wedge can be locked in place manually to allow the aircraft to be despatched, but this still results in a delay."

Sirisena explains that the problem has occurred due to "wear and tear issues that surfaced after flight-test" and that Airbus devised an interim "work-around" - to taxi straight for 50m (165ft) before making a turn.
Williams says that the problem has now been fully addressed in two ways. "The wedge sensor was too sensitive so that has been redesigned, and a greasing procedure was worked out which actually did more [to fix the problem] than the sensor. We now think that this problem is behind us," he adds.Another gear-related problem blighted SIA - and resulted in an in-flight turnback - which was caused by the system for the undercarriage doors, which incorrectly detected them as being open."There have been rigging issues on gear-doors and sensors and we've improved the procedures on the production line to make sure we've got the tolerances set up properly," says Williams.

A happier tale is the A380's performance, which has bettered expectations. "Meeting the performance guarantees doesn't come into it, she's ahead of her nominals," says Clark."The faster the A380 flies the less fuel it burns. Long-range cruise is Mach 0.85, if you fly at Mach 0.83 the fuel burn increases."Qantas's Strambi concurs: "The A380 has met or exceeded all the original performance, noise and fuel burn guarantees made by Airbus at the time the aircraft purchase decision was made."Clark says that because of the "favourable mach bias, there's quite a marked increase in terms in fuel reduction as you increase the cruise speed to Mach 0.85".

Emirates' GP7200s have also behaved well during their first year in service, showing what Clark believes is an unprecedented "zero degradation" in performance. The airline has had two precautionary in-flight shutdowns, but neither was caused by the machinery, says Clark. "They were indication issues."
With two airlines operating a fleet of 14 Trent 900-powered A380s, the R-R fleet has accumulated significantly higher utilisation than the GP7200 to date - more than 225,000h against 81,400h.
Sirisena says that SIA's Trent 900s have suffered "some teething issues" and the fleet has undergone "a lot of engine changes to address early signs of potential problems.
Rather than let the problem develop, Airbus and R-R have taken preventative action."
SIA has suffered three in-flight shutdowns, one of which was caused by fuel starvation and one by a quality/installation problem that caused an oil line to crack. The third incident, which occurred in September, was a precautionary shutdown after the crew received a warning and is still under investigation.
SIA Trent 900s have undergone a series of upgrades with changes including solenoid valves, electronic controls, bleed valves, fuel meeting valve units and wiring connectors, while high-pressure nozzle guide vanes have been replaced to address premature burning, says Sirisena. The latter issue resulted in the A380's first airworthiness directive.

Meanwhile, SIA's oldest A380 (MSN003/9V-SKA) underwent the first C check maintenance inspection in September, having accumulated more than 8,000h and 1,000 cycles. The inspection, which has a two-year interval, was undertaken at the airline's Changi base with a "small army of Airbus people in attendance - about 100 folks", says Williams."We did some deeper inspections than we'd normally do in a C check and discovered some small things for us to follow up, but there were no major issues," he adds.
The aircraft was brought up to the latest modification standard in parallel with the inspection. As part of the inspection, Sirisena says that the airframe was giving "a health check, we were looking to see if there was the potential for rubbing" that may not have been identified during ground- and flight-testing.

"When you fly with a full passenger load there are different vibratory stresses than during flight-testing. Once an aircraft is in the air things flex, twist and turn, alignments are different and there are vibrations, stresses."

This phenomenon has already seen some "transitory vibrations" identified in the plumbing for the A380's 345bar (5,000lb/in2) hydraulic system, Sirisena says. "We've seen some strange movement in the plumbing."However, Williams says that Airbus "has not seen vibration as being an issue that has come up".

Pilot's perspective
SIA's flight operations chief Capt Yeap says that SIA operates its A380s with ratio of around 10 to 11 flightcrews per aircraft. He says that pilots have "transitioned easily" to the aircraft's size as many were already familiar with 747-400. Transition time is about three months, the same for other types in the fleet, he adds."Crews are very happy after their first circuit. The A380 is a well-designed aeroplane, the flight-control laws are very advanced and it is responsive for its size and accurate to fly," Yeap says.

On the ground, the A380 manoeuvres like the 747 - "a gentle oversteer", he says. "The major difference is the inertia. The steering is fly-by-wire, so it is not an instinctive input like normal direct controls and takes a little bit of getting used to."Normal procedure is to use the taxi camera, "but with experience, any competent crew will be able to taxi without it", adds Yeap.The A380 has impressive performance once off the ground - "we can achieve optimum climbs with no problem" and it also slows down well, he adds.
SIA generally cruises its A380s at M0.83-0.85, and the approach speed - for a landing weight close to the 397t maximum take-off of a 747-400 - is an impressively slow 130-135kt (240-250km/h).The three A380 operators deploy their fleet across the globe serving destinations in North America, Australasia, the Pacific Rim and Asia. All three fly between London and Sydney - with Qantas shadowing SIA's routing via Singapore, while Emirates flies through its Dubai hub.

All the airports that the type serves have been well prepared for the aircraft. "With air bridges to main and upper deck passenger enplaning and deplaning is poetry in motion," says Clark. Turnaround times range from 90-110min, depending on route and operator. For example, Emirates does 90min turns at London Heathrow between the inbound EK001 and outbound EK002, says Clark. And replenishing main and upper deck galleys using standard and special scissor-lift trucks has not been problematic. "We've never had to use the cart lifts," he adds.
Looking forward

Clark says that as its A380 fleet grows next year, new destinations for the type are likely to include Paris and Seoul and he wants to return to New York - where it inaugurated its A380 operations in 2008 - by June. Tokyo Narita is also a potential future destination.While there are planned dates for new A380 routes, Clark concedes that these are contingent on Airbus meeting the delivery schedule. "We still have some niggling delays from Toulouse - they're still not stable on the production side."
He meets Airbus chief executive Tom Enders and programmes boss Tom Williams regularly to discuss the delivery schedule, but remains concerned about Airbus's ability to maintain the delivery stream to incumbent customers as "heads of version" come through for new operators such as Air France and Lufthansa.
The Emirates A380s are notable for the fact that they are equipped with a pair of in-flight showers for first-class passengers, which have proved very popular, says Clark, although he concedes he "got the maths wrong" on the amount of water to uplift.

"We put 2.5t in the aircraft, but we're only using 60% - even with every first-class passenger taking a shower - so we've reduced the potable water we carry," Clark adds.Because of weight growth during development, initial production A380s are around 5-6t behind the target manufacturer's weight empty (MWE) says Clark.
On top of this, the rewiring required for early production aircraft added another 400kg (880lb) to the weight, he claims. However, Airbus is incorporating weight savings into later-build A380s to bring weight back in line with guarantees and Clark expects the gains will ultimately create an aircraft that can serve certain US West Coast destinations direct from Dubai.

He forecasts that A380s being delivered by 2012 will have MWEs "a minimum of 2t lighter" than today's aircraft, which, combined with reductions in the weight of the airline's operator items (a new generation of lighter seats, for example) means "you've got an aircraft that can fly 15h 45min and can do the West Coast".
He is "optimistic" that this will bring San Francisco into range, but concedes the A380 will always be challenged to get as far as Los Angeles. "She was never designed for that mission," he says.The A380's nominal maximum take-off weight is 560t, with an option of 569t (and further growth available from 2012).
Clark says that Emirates flies its A380s at between 510t and 540t, as it does not need the full weight and takes the benefit of lower landing fees.Clark sums up the A380's appeal in raw statistics. "We're busting the seams on the aircraft. We're consistently getting 90-100% load factors - its popularity hasn't dissipated in a year. And if Dubai International airport grows to where we want it, we'll ultimately have more than 58 in our fleet."

Manufacturer's view
Airbus acknowledges that it has "still got work to do" to get the A380's reliability to match the level of the passenger appeal it has delivered during its first two years in service."Keeping in mind the level of technology that we've brought to the aircraft, it's been encouraging to see the level of performance that we've got - but we can do better," says Airbus executive vice-president programmes, Tom Williams. "We've still got some work to do."When the A380 entered service two years ago with Singapore Airlines, Airbus laid on an extremely intense network of "enhanced support", positioning additional engineers, mechanics and personnel from Toulouse into Singapore and the first outstation, Sydney.
A similar amount of assistance has been provided for Emirates and Qantas, and those support levels remain "heavy", says Williams. "As each airline takes more aircraft they open up new routes, so we're having to extend support. Although this was always envisaged, we're certainly providing a heavier level of support than we originally planned."

Williams concedes that Airbus was "disappointed" and surprised about problems that began to crop up after a strong first few months of operation, given the preparations it had made. "We used the extended time between certification and delivery to do a lot of extra flying work on maturity. But we still encountered things when we went into service that hadn't shown up before."Why? Because there are a different set of pressures during testing to what an airline experiences.
The operators have put it into a very intense operation - straight on to premium routes with very fast turnarounds."Williams adds that the exceptionally good first few months with SIA's initial aircraft - where there were no technical delays or cancellations - may have mislead the airframer, as problems then begun to occur as the fleet and network expanded.
To begin addressing the much-criticised nuisance fault warnings that Emirates in particular fingers as the culprit behind the ongoing disappointing technical despatch reliability, a new software upload has been implemented."We've just issued a new 'batch 2' software which we think will cut out about 40% of the nuisance messages as it is often information that the pilot can't really do much with," says Williams.
He says that Airbuses have a reputation with flightcrews for being too "talkative" and this has been compounded by the newness of the A380. "With a new aircraft all the default rules are probably much more stringent as people are learning how to use the aeroplane."The crews have a feeling that the aircraft is talking to them too much - telling them things that are interesting but not really essential - and the pilot's default will be 'let's not go'."SIA's senior vice-president flight operations Capt Gerard Yeap highlights the potential pitfalls of aircraft systems providing too much data: "We have to be careful we don't have information overload - that we don't fall into the trap of wanting to know so much you end up not knowing anything".
Williams says another issue that has led to unnecessary delays or cancellations is the fact that as the A380 is a new type, the minimum equipment list was initially written in "a very strict way because you're gaining experience of the aeroplane. So from the customers' point of view he may see something flagged as a no-go item on an A380 that wouldn't have been on an A330."Faults flagged on the aircraft's post flight report (PFR) are investigated by the troubleshooting manual (TSM), which can be a lengthy process if there are, say, six potential root causes to be checked, says Williams. "
The airlines have asked for a bit more prioritisation of the TSM, as statistically there are some problems that are the more likely ones which should be eliminated first. But this requires experience of the aircraft and is something that over time you build up a better understanding of."

Williams shares Emirates Airline president Tim Clark's doubts about any early success in the fleet reaching the 98.5% TDR target. "I think we're closing on it pretty fast, but not by the end of this year. I'd be confident we'd be there by the middle of next year. We've still got a bit of work to do."The spurious error-message woes have been further heightened by issues with sensors in certain parts of the aircraft, such as the nose-gear and body-gear steering systems, and fuel quantity management system.
These were due to either over-sensitivity, water contamination that confused the logic, or a combination of the two, and have been addressed by design changes to the sensors.Williams says the reliability improvement drive is being aided by "a combination of pro-active and reactive design work going on from engineering point of view. We're taking the operator experience we've had now and looking at things again with design engineers so that we can have a more robust design."Pressure is also being applied to certain suppliers to up their performance: "We've got guarantees with all our suppliers on MTBR [mean time between unplanned replacement] and there are a few who are still not quite there yet".
Airbus is rolling out additional innovations on the A380 in the coming months, including the electronic logbook (a function of the on-board information system) and brake to vacate (BTV) autobraking functions. "The E-logbook is part of Airbus's evolution to a more paperless cockpit. We have one operator trialling it and the rest will have it on a test basis by the end of the year," says Williams.BTV, which enables the pilot to designate the runway exit point and allow the autobrake to modulate the retardation, is being debuted by the latest A380 customer, Air France.

Engine makers' views
As lead engine supplier on the A380,
Rolls-Royce's 70,000lb thrust (312kN) Trent 900 powered the aircraft on its maiden sortie on 27 April 2005 and the bulk of the test fleet during the flight trials and certification programme. The Trent has been selected for nine of the 16 customers so far and is used by two of the three airlines operating the type - Singapore Airlines and Qantas - which account for 14 of the 20 aircraft delivered.R-R's rival on the A380 - General Electric and Pratt & Whitney's Engine Alliance joint venture - could be described as a "one-trick pony" because the double-decker is the only application for its single product, the 70,000lb-thrust GP7200.

The US company has just six customers (including Air Austral's two-aircraft commitment), but has been selected to power more A380s than R-R in unit terms (94 firm/two commitments versus 90 firm) and has laid claim to the biggest prize on the programme so far - Emirates with its 58 aircraft on order.
Richard Keen, who is R-R's head of marketing for Airbus programmes, says that although "a lot of useful lessons were learnt" from the extensive flight-test programme during which the Trent-powered A380 test fleet accumulated 22,000 flying hours, "you will always see new issues once the aircraft goes into service".Launch operator SIA has made precautionary Trent 900 engine changes that Keen attributes to the careful approach the airline took to the A380's introduction.
"SIA wanted to do everything to protect its operation in an absolute way, which we fully supported.
If it saw anything that might be a future operational risk, it took a precautionary approach that necessitated an extra engine change or two."Trent 900 marketing manager Elise Hresko says that the precautionary engine changes were generally in response to post-flight advisory messages on the maintenance report. "They were genuine alerts - rather than nuisance warnings - but the engine was still within limits," she says.
"At the beginning of the operation, the limits had been drawn in a very conservative manner to help us understand the engine's behaviour."Keen says that all the "teething problems" suffered by SIA have been "closed out or contained" under R-R's "project zero" programme, which "is a zero-tolerance approach to operational disruption".
He adds that the Trent 900 operated for seven months at 100% reliability and the "disruption index" now stands at 99.8%, which is line with a mature Trent product.R-R has identified that the first two of SIA's three in-flight shutdowns were "non-basic", says Keen, which means the engine's basic design was not at fault and nothing has had to be changed. "We're waiting to see what caused the third shutdown as the engine is undergoing strip-down and inspection."Engine Alliance says the five GP7200-powered A380s flying with Emirates have a 99.9% "departure reliability rate", have suffered no engine-related in-flight shutdowns or aborted take-offs and have an unscheduled engine removal rate (per 1,0000 engine flying hours) of 0.051 (all figures are 12-month rolling averages to October 2009).

Emirates has been delighted with the GP7200 so far
Emirates president Tim Clark says the engines powering his A380s have performed well and had no major issues.Engine Alliance president Jim Moravecek says that the
GP7200's fuel burn came in 0.9% ahead of Airbus's specification, which gives it a 1% advantage over its rival.R-R's Keen disputes this claim, but the engine maker is working on a two-pronged development programme for the A380's Trent, the first of which, the 900EP, has been launched and is available from 2012.
This upgrade, which is not retrofittable, involves the incorporation of elliptical blades and vanes to the high-pressure and intermediate pressure compressors, and will deliver a 1% improvement in fuel burn. Further improvements, borrowing technology from the Trent 1000 and XWB, are in the pipeline, Keen adds.

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