Assembling the Super Jumbo
It's bigger than a Goodyear blimp. It's bigger than a Boeing 747. It's even bigger than a Lockheed-Martin C-5 Galaxy. In fact, the new Airbus A380 super jumbo jetliner is the biggest thing in the sky.
Earlier this year, the first 555-seat aircraft rolled off a huge assembly line in Toulouse, France, and took its maiden flight. It is currently undergoing a wide variety of flight tests that are necessary for certification. Airbus officials boast that the A380, which is due to enter service in 2006, is the most advanced, spacious and efficient airliner ever.
The statistics alone are staggering. For instance, the A380 offers 35 percent more seating than its closest competitor-the Boeing 747-400, which can hold up to 416 passengers. Although most aircraft will be configured with three seating classes, the airliner could accommodate up to 840 passengers in a one-class configuration.
The double-decked behemoth features a 261-foot wingspan-50 feet wider than a 747-that can hold up to 41,000 gallons of fuel. The upper deck runs the length of the plane, but it isn't as wide as the main deck.
Airlines that have ordered the aircraft claim they want to create a new kind of flying experience for their passengers. With 49 percent more floor space than its rival, the A380 is capable of being outfitted with unique onboard amenities, such as a business center, a health club, a cocktail lounge, a casino, a shopping arcade, a conference room, a day-care center or a library. Other unique features include onboard showers, wheelchair-accessible toilets and first-class seats that fold down into beds.
The 79-foot tall aircraft-the tail is approximately the size of a seven-story building-is 14-feet taller than the giant C-5 Galaxy transport that is used to airlift tanks, helicopters and other military equipment. An empty A380 weighs 610,700 pounds vs. 399,000 pounds for a 747-400. Maximum take-off weight for the A380 is more than 1.2 million pounds vs. 840,000 pounds for a C-5 Galaxy. Indeed, everything about the plane is big, including its price tag: $285 million.
Despite the sheer size, Airbus executives claim that the A380 will use 20 percent less fuel and fly quieter, cheaper and more environmentally friendly than the 747, which has reigned as heavyweight champion of the skies for 35 years. According to Charles Champion, executive vice president of the A380 program at Airbus, his aircraft's efficiency and advanced technology result in 15 percent to 20 percent lower seat-mile costs. And, its 8,000-mile range is 10 percent greater than other large aircraft.
"The aircraft's significantly reduced noise and emissions levels will help to minimize its effects on the environment," claims Champion. "Its new-generation engines and advanced wing and undercarriage design mean the A380 will not only comply with today's noise limits, but will be significantly quieter than its rival, producing half as much noise on take-off."
Composites and other lightweight materials help reduce weight, making the A380 "a highly fuel-efficient aircraft. It burns 12 percent less fuel than its competitor, reducing exhaust emissions," Champion points out. The super jumbo can be powered by four Rolls-Royce Trent 900 engines or GP7200 engines from the Engine Alliance (a General Electric and Pratt & Whitney joint venture).
Airbus has 145 firm orders for the A380 from 14 customers, totaling more than $40 billion. The aircraft appeals to airlines with long-haul routes, such as Los Angeles-Sydney, New York-Beijing or Paris-Rio de Janiero. Singapore Airlines will be the first to fly the super jumbo on its 6,739-mile London-Singapore route. It is scheduled to take delivery of the aircraft late next year.
Other airlines that have ordered the plane include Air France, China Southern, Emirates, Lufthansa, Qantas and Virgin. In addition, a cargo version -the A380F-has attracted orders from companies such as FedEx Corp. (Memphis, TN) and United Parcel Service Inc. (Atlanta).
Is Bigger Better?
Engineers at Airbus took a "bigger is better" attitude when developing the A380. They believe it is more efficient to fly large passenger loads from hub to hub.
"Airbus argues that congested hub-to-hub flying and future air travel growth justifies the A380," says Scott Hamilton, president of Leeham Co. (Sammamish, WA), an aerospace consulting firm. "Boeing has staked its future on the market fragmentation theory."
Nevertheless, the record-breaking A380 is very controversial. Airbus S.A.S. (Toulouse, France) is a consortium owned by the European Aeronautic Defence and Space Co. (EADS, Amsterdam) and BAE Systems plc (Farnborough, England). The company has been funded by low- or zero-interest loans from large European nations, such as England, France, Germany and Spain, where its factories are located. In fact, some experts claim that the A380 is the most heavily subsidized plane in history. Airbus has received millions of dollars to cover start-up costs for the super jumbo project.
Although the A380 is assembled in Europe, Airbus officials point out that many key components come from the United States. "Fifty percent of the components and subsystems will be made in the United States," claims Allan McArtor, chairman of Airbus North America Holdings Inc. (Herndon, VA). Indeed, major suppliers include Alcoa Inc. (Pittsburgh), Goodrich Corp. (Charlotte, NC), Hamilton Sundstrand Corp. (Windsor Locks, CT), Honeywell Aerospace (Phoenix), Parker Hannifin Corp. (Cleveland) and Rockwell Collins Inc. (Cedar Rapids, IA).
At the same time, some observers have questioned the practicality of the giant aircraft, claiming that it's a publicity stunt. However, Airbus responds to those critics by pointing out that it has spent more than 5 years and more than $13 billion to develop the jetliner. "An array of new technologies for materials, processes, systems and engines have been developed, tested and adopted for the A380," says Champion.
But, the A380 program has been plagued with minor development problems. As a result, first deliveries have been delayed half a year due to unspecified "engineering complexities."
Airbus engineers have been struggling to reduce the weight of the aircraft. For instance, they decided to use aluminum instead of copper wiring for the electrical system. At the recent Paris Air Show, Noel Forgeard, Airbus president and CEO, acknowledged that there have been "some industrial issues and delays, especially on [wire harnesses]."
In addition, some airport operators are concerned about the massive size of the aircraft, which will require expensive modifications to existing runways and terminals. Many ramps and taxiways must be repaved to be wider and thicker.
Most existing airports simply cannot accommodate the A380. The plane is so big that major U.S. airports, such as Chicago O'Hare and Atlanta Hartsfield, would need multimillion dollar overhauls to allow it to land, pick up passengers and take off. To ease congestion, the super jumbo uses a double-deck ramp system with widely separated doors that allow passengers to board and exit the aircraft simultaneously.
Officials at one major airport, San Francisco International, claim it will cost them more than $76 million for new facilities and improvements to handle the super jumbo. To pay for updated terminals, runways and other infrastructure, airport operators may be forced to levy special charges or taxes against airlines using the A380.
Despite those issues, Airbus claims that the A380 represents the future of commercial aviation. In fact, Champion calls it the "flagship of the 21st century." With air travel expected to continue growing-many forecasts call for it to double over the next 20 years-commercial aviation is approaching gridlock. Champion says the A380's ability to carry more passengers will help ease some of that congestion by transporting people without additional aircraft movements.
The A380 will serve routes between large cities, using megahubs. Many of those airports are already congested, so Champion argues that the super jumbo will actually help alleviate some of the problems by reducing the number of takeoffs and landings.
"By 2023. . . major airlines will need 1,250 very large and economical aircraft like the A380," predicts Champion. He says demand for super jumbos will be centered in the Asia-Pacific region, which will account for 62 percent of worldwide demand. For instance, by 2010, Champion expects A380 air carriers to make more than 100 flights a week to and from China.
Some critics scoff at that optimism. But, for those who claim the A380 is too big, a little bit of history is worth considering. "When the 747 entered service in 1969, the airline industry was in a depressed state and the airplane capacity was, indeed, too large," Leeham's Hamilton points out. "Airlines put amenities in them [such as piano bars] to take up space instead of having rows and rows of empty seats. But, air traffic grew into the airplanes and now the amenities are gone, replaced by rows and rows of narrowly placed seats."
Multinational Assembly Line
Components and subassemblies for the A380 are built in several different locations around Europe. For instance, the aft fuselage and the forward fuselage are assembled in Hamburg, Germany. The rear fuselage and tail cone are assembled in Getafe, Spain, and flown to Hamburg where they are attached to the aft fuselage. The fuselage sections are then transported by ship to Mostyn, Wales, where wings made in Broughton, Wales, are loaded onboard.
The ship then sails to Saint Nazaire, France, where the cockpit, nose and center fuselage are assembled. The nose is attached to the forward fuselage at this point. Then the ship continues to Bordeaux, France, where the fuselage sections and the wings are loaded onto a barge, along with the horizontal tail plane, which is assembled in Puerto Real, Spain. All of the subassemblies are transported by a special truck convoy to the final assembly plant in Toulouse, which is located in south-central France.
At the 120-acre facility, major components, such as wings, vertical and horizontal tail planes, and fuselage sections, are joined and the full airframe takes shape for the first time. "Final assembly includes integration of the systems in the cockpit; joining of forward and aft fuselage sections; joining of the wings to the center fuselage section; and installation of the horizontal tail plane, fin, engine pylons, landing gear and engines," says Champion. "Systems tests are also carried out on electrical wiring, landing gear, fuel tank pressure and adjustment of the control surfaces."
Cabin furnishings and interior trim for the super jumbo are installed in Hamburg, along with fuselage painting, prior to final delivery. "The interior logistics are challenging from the perspective of size and customer specs," notes Champion. For instance, he says the "sophistication of the cabin definition impacts the electrical harnesses."
Four A380s that are being used as test aircraft have already been assembled. Three more aircraft have passed through the final assembly station in Toulouse.
The final assembly line is currently geared to producing four A380s a month, but it has the capacity to produce more if required. According to Champion, the final assembly process takes 90 days. Digital simulations were used to design lean production processes and plant layouts.
Airbus is currently revamping its production processes to cut costs, reduce lead times and eliminate waste. The current initiative, dubbed Route 06, aims to slash $1.8 billion. According to Forgeard, the goal is "great productivity gains implemented on the production and final assembly lines, with lead time reduction for greater flexibility." For instance, the assembly facility in Hamburg is shifting to a moving line. It is expected to boost productivity by 35 percent and reduce lead time by 45 percent.
To operate more efficiently, Airbus management is also streamlining the decision-making process on the shop floor. Management hopes to speed up problem solving and encourage more cross-functional teamwork. "The key is communication with our teams at every level," says Champion.
The A380 uses a variety of lightweight materials to counterbalance the aircraft's massive size. For instance, Airbus engineers are making extensive use of carbon fiber-reinforced plastic. The A380 features a carbon fiber center wing box, which shaves up to 1.5 tons off the aircraft compared to traditional aluminum alloys.
A monolithic carbon fiber design has also been adopted for the fin box and rudder, as well as for the horizontal tailplane and elevators. In addition, the upper deck floor beams and rear pressure bulkhead are made of carbon fiber. The wing skins are constructed from advanced aluminum alloys. And, the fixed wing leading edge is manufactured from thermoplastics.
According to Champion, 40 percent of the aircraft's structure and components are manufactured from state-of-the-art carbon composites and advanced metallic materials. In addition to being lighter than traditional materials, he says they offer significant advantages in terms of operational reliability, maintainability and ease of repair.
After extensive research, Airbus engineers decided to incorporate a new type of lightweight material that has never been used on a commercial airliner. Part of the upper fuselage shell of the A380 is fashioned from glass-reinforced aluminum (GLARE), a laminate comprised of alternating layers of aluminum and glass-fiber reinforced adhesive.
The material was developed jointly by engineers at Delft University of Technology (Delft, Holland) and the National Aerospace Laboratory (Amsterdam). It took several years, including the development of special tools, to perfect the assembly process to the point where it produced acceptable joints.
"We can produce strong, homogenous and large construction parts without the usual, additional expense of drilling and riveting," claims Arnt Offringa, head engineer at Stork Aerospace Industries (Papendrecht, Holland), which manufacturers the innovative material.
GLARE panels are laid up in a mold and cured in an autoclave with aluminum stringers bonded to the inside surfaces. The panels are made by placing several aluminum sheets, butted together, in a single layer into a mold that is cured at a temperature of 350 F. According to Offringa, GLARE panels have a small degree of residual tensile stress from the curing process, which can be used to increase structural strength.
The skin material can be anywhere from 5 percent to 15 percent lighter than aluminum. However, it is less bendable than monolithic aluminum. And, the panels cost 3 to 10 times as much as equivalent assembled aluminum panels.
In addition to being less dense than aluminum, for a weight-savings of around 800 kilograms, GLARE has proven superior in terms of fatigue. For example, tests have demonstrated that an artificial crack subjected to thousands of flight cycles barely increases in size.
The new material also resists corrosion. The first glass-fiber layer prevents any penetration beyond the superficial aluminum coating. Champion says GLARE is made with a hot-bonding process, but is repaired in the same way as standard aluminum.
"The net weight-savings resulting from these innovations allow the A380 to weigh in at around 240 tons-a full 10 to 15 tons lighter than a similar-sized aircraft using 747 technology," says Champion.
Tests also show that the aerodynamic performance of the aircraft is significantly enhanced. "Better aerodynamics and lower airframe weight reduce the demands placed on engines and translate into lower fuel burn, reduced emissions into the atmosphere and lower operating costs," says Champion.
A critical piece of the A380 is the huge center wing box. It is comprised of seven large parts made out of carbon-reinforced plastic, which is a mix of 60 percent carbon fiber and 40 percent resin. Though relatively light, the wing box structure is able to withstand high levels of stress thanks to an increase in the thickness of parts.
"The development of thicker parts has led to an evolution in tooling technology and the requirement for increased production rates of tools, such as a new-generation automatic tape-laying machine," explains Champion. Until recently, he says production using carbon-reinforced plastic has been primarily a manual process.
The automated tape laying machine heats carbon fiber tape and lays it over predefined shapes. It can manufacture both flat and contoured shapes, enabling the production of complex designs and large surfaces, such as the upper base skins of the A380 horizontal stabilizer. According to Champion, this assembly process has cut tooling costs by 20 percent and reduced lead times by 50 percent.
New Assembly Processes
The unique size of the A380 required Airbus engineers to develop many new facilities and new methods to manufacture and assemble components. "Some [of the innovative manufacturing processes] have proved so advantageous they have gone into series production on other existing Airbus aircraft programs," says Champion. "And, lots of things we've learned about on previous programs have come into play on the A380."
One example is laser welding, which is used to attach stringers-longitudinal reinforcements-to the lower fuselage skin, instead of traditional riveting. "This technique not only engenders a potential weight reduction, it is also much faster than conventional riveting," claims Champion. "Eight meters of stringers can be laser welded per minute."
By using laser-welding technology, considerable time is saved during the assembly process. "While joining parts on a fuselage shell can take 5 hours using conventional riveting techniques, laser welding can join the same components in just half an hour," notes Champion.
The laser-welding process used by Airbus includes a built-in automated inspection unit. "Tests run on the resulting structures to determine damage and fatigue tolerance have demonstrated that they behave as well or better than conventional alloy construction," says Champion. "A further advantage of this [production] technique is that it eliminates fasteners, and thereby the major source of corrosion and fatigue cracks."
For example, Airbus engineers are looking at other metal components of the A380 that could be joined using laser welding. In addition, they are making extensive use of laser positioning to improve quality and boost productivity.
Airbus engineers use the technology to control and align the assembly of large components, such as fuselages and wings. With indoor GPS systems, assemblers can measure parts precisely and determine exactly where they fit in an airplane.
Technicians use a handheld wand that is hardwired to a wearable computer to detect infrared light signals from transmitters located on different parts of the assembly line. Each transmitter sends out strobe signals and fan beam signals as it rotates on a stand. As an end user moves the wand from one location to another, it uses the same arrival times of all the different transmitter signals to calculate the spatial coordinates of its tip.
Despite heavy use of lightweight materials, early versions of the A380 were reportedly more than 10,000 pounds overweight. As a result, engineers were forced to scramble for solutions. For example, they decided to use GLARE, instead of conventional aluminum, to manufacture the leading edges of the horizontal and vertical stabilizers. However, that decision increased production costs. In addition, suppliers were urged to lower the weight of galleys, lavatories, seats and other interior components by 30 percent.
The sheer size of the A380's wings-each one is 120 feet long, creating a total surface area of 9,100 square feet-makes their assembly a huge challenge. Airbus engineers decided to make the 24 largest ribs-out of a total of 61-in each wing out of composite material. Each of the composite ribs is encased in an aluminum frame. Of course, new production methods had to be developed to accommodate this change.
That's just one example of numerous production obstacles that had to be overcome to build the super jumbo. "A lot of it has to do with size," says Champion. "The scope, shape and flexibility of the various parts and components to be assembled was a big challenge. For example, the wing covers with creep forming, stringers, wing-to-fuselage junction-all these elements, at both the subassembly and assembly stages-had extremely minor tolerance for specs."
Traditionally, wing panel assemblies are built on manual jigs. It is a labor-intensive assembly process that requires numerous operators. To assemble the A380, Airbus engineers have made extensive use of automation.
"A fundamentally new approach to the assembly tooling was required," says Peter Zieve, president of Electroimpact Inc. (Mukilteo, WA). His team of engineers developed special jigs that hold the immense wings, which measure 36 by 148 feet. Each 33-ton wing is almost 10 feet thick at the end that attaches to the wing box.
The port and starboard wings are assembled using a mammoth machine that automatically drills more than 150,000 holes and installs fasteners. The 700-foot-long, four-story tall, 150-ton E4380 is located at the Airbus wing factory in Broughton, Wales.
"The work is fully automated," says Zieve. The basic wing is formed by fastening together a ladder-shaped structure of front and rear spars with transverse ribs. Then, the upper and lower skins are added. The panels and stringers are clamped in place on an integrated fixture. The riveter moves along rails and does all the fastening. According to Zieve, approximately 150,000 rivets are used in the assembly process.
The machines install both rivets and lockbolts of all sizes between 0.25 inch and 0.5 inch in diameter with a stack range up to 2.5 inches. A total of six machines are currently in use at the wing plant, and two more are on order.
There are four assembly lines at the Broughton plant: two (port and starboard) each for the upper and lower wing panels. Each tool holds both a port and a starboard wing. "Four machines work for one week" to assemble an A380 wing, explains Zieve.
The E4380 gantry riveting machine is designed to operate on the curved upper and lower surfaces of wing panels. To improve toolpoint alignment, Zieve and his colleagues added a Z-axis that moves the yoke to reduce the necessary travel envelope of the clamp table axes. To get the machine to be flexible, while maintaining stiffness, the engineers had to add a true Z axis.
The machine gantry consists of two towers with a slideable arrangement between. Each tower is independently driven in the long X axis. The yoke is trunnion-mounted to the two towers so that it slides across the face of each. The wing fixture is in the center, vertically arranged. The yoke straddles the wing panel to access the fastener locations.