The final countdown

The last stage of Eurofighter production is swinging into action, and the final assembly process is hallmarked by innovation, ground-breaking technology and a new manufacturing philosophy, reports MARK VENABLES

September 8 this year marked a significant milestone in the Eurofighter Typhoon project. On that day, final assembly of the firstof 232 Eurofighters for the RAF began at BAE Systems in Warton, marking the culmination of years of effort.

As Graham Ashton, final assembly team leader says: ‘The Eurofighter team are extremely optimistic and feel they are at the dawn of a new adventure.’ Eurofighter is no ordinary aircraft. It has been designed to meet a stringent and wide-ranging list of capabilities compiled by its customers. Its abilities in the air are matched by a buildprogramme which utilises lean production methods to a degree unprecedented for a military aircraft, in an effort to slash both build time and cost.

Eurofighter will be the flagship of the UK aerospace industry and the backbone of BAE’s business at Warton for the next 15 years. Production has been split between the four partner countries in a complex workshare arrangement. BAE Systems is responsible for the front fuselage, canard wings, windscreen and canopy, dorsal spine, vertical stabiliser, inboard flaperons and stage one of the aft fuselage. In Italy, Alenia assembles the left wing, outboard flaperons and both the second and third stages of the aft fuselage. In Spain, Casa manufactures the right wing and leading edge slats, while the German contribution from Dasa concentrates on the central fuselage.

The production workshare is split to take into account the final numbers of aircraft ordered by each nation. The UK takes 37.5%, Germany 30%, Italy 19.5% and Spain 13%, although each country will have its own final assembly line.

In the UK, this will be based in 302 hangar at Warton, opened in 1977 and previously the location for Tornado final assembly. The hangar has been completely refurbished and was handed back from Ballast Wiltshier to BAE Systems in June this year. Since then, the final assembly team has been preparing the area for production. This has included the installation of IT systems and equipping and staffing the plant in preparation for receipt of tooling and handling equipment.

Production makes some significant departures from previous practice, in military aircraft assembly at least. ‘The whole process has been based on bringing value to the aircraft position, rather than moving the aircraft to add value,’ says Ashton. This means the aircraft stays in one place instead of repeatedly being moved along a production line, reducing the amount of non-value added work being carried out.

The assembly shop boasts numerous innovations. Among these are an automated laser alignment station. The hangar layout and nose-in docking bays have integral services, removing the need for dedicated rigs within the hangar. Access staging provides more comfortable access, and the testing sequence has been modified to delay the need to install expensive equipment until absolutely necessary, further reducing work in progress.

There are no stores, forcing the teams to operate a lean environment, where equipment is delivered just-in-time. A wireless LAN will be installed, to improve communication within the hangar.

One of the principal aims is to make Eurofighter the first aircraft in which spare parts are genuinely interchangeable. In the past, panels were individually modified for each aircraft with the result that a tail fin panel, for example, could not be removed from one Tornado and fitted to another.

In order to achieve the required accuracy for interchangeability, extensive use has been made of lasers in the manufacturing and assembly of theaircraft, particularly in the alignmentstation where the various sub-assemblies are first married up. A Leica laser tracker performs measurement checks on profile, hole position and surfaces using Datamyte software to collect data for analysis.

‘The overall design of the facility has been based on the civil aviation market concept of positioning the jet in a workstation “dock”, and “wrapping” it with access staging,’ says Ashton.

‘The new layout for the hangar has been based on a three-team concept,’ he continues. ‘Team one will receive the aircraft, prepare it for alignment, then lift and position the main units into the alignment facility. After the fuselage has been aligned and married together, the team will install the wings andcomplete the mechanical and electrical elements of the airframe. Team two will equip and test the aircraft prior to preparing it for engine ground runs. Team three will carry out engine runs and prepare the aircraft for its flight test programme.’ Once assembly has been completed, each Eurofighter will be moved to the spray shop prior to acceptance by the customer.

At maximum capacity the hangar will hold 15 aircraft, and will produce 20 jets a year by 2004. A target has beenset of a 16-week build by the time the twentieth jet is finished. ‘The drive to a 16-week performance is based on ensuring that all resources, including equipment, aircraft details, facilities and personnel are available to the aircraft when needed,’ says Ashton.

He adds that the normal Tornado production cycle was approximately 30 weeks, but the quickest final assembly of a Tornado was 14 weeks. This was achieved by ensuring all relevant equipment and facilities were available to this particular aircraft, and, like Eurofighter, the assembly was undertaken in a static work station and not on a moving production line. ‘We are very confident that our production philosophy makes the 16-week target a realistic goal,’says Ashton.

Potential bottlenecks have been removed or reduced by ensuring that all build stations have identical facilities for the assembly and testing of the jet.

‘The two areas of risk are the alignment facility and the fuel test facility,’ says Ashton. ‘Within the alignment station potential risks during assembly of the aircraft have been reduced by careful rehearsal and by providing a traditional assembly facility as a fallback should we have a catastrophic equipment or process failure,’ he adds.

The foundations have been laid for a second alignment station, should increased orders create a bottleneck. The fuel test equipment can test aircraft at two adjacent locations. If the system fails then existing mobile fuel rigs can be used.

Looking at the wider commercial environment, the traditional system of cost-plus manufacture has been swept away. ‘The relationship between the prime supplier and the rest of the supply chain has had to change from supplier/customer to a partnership where both parties strive for win-win situations,’ says Ashton.

Over at BAE Systems’ Salmesbury site, where the front and rear fuselage are being assembled for all 620 aircraft on order, Eurofighter has set entirely new challenges compared with those posed by the previous project, the Tornado. These included reducing build time by half, reducing the ratio of maintenance to flying hours from 16:1 to 9:1, and cutting the defect rate per flying hour from 1.23 to 0.40.

A new manufacturing philosophy Achieving these targets required acomplete change of approach. Out went the traditional ‘over the wall’ methodology, in which the separate divisions of marketing, product development, engineering, manufacturing and customer support completed their allotted tasks before passing the project down the line.

The solution BAE Systems adopted was to create design-build teams defined by product disciplines – electrical, mechanical, structures and weapons; and integrated product teams (IPTs) aligned by product – front fuselage, rear fuselage and final assembly. Each team is fully complemented with the skills that were previously split across fivecategories and each has total control of its budget.

Under this system all the product teams work concurrently. Design is carried out on Catia CAD/CAM software across the four partner nations, an approach which shifts the majority of design changes into the early concept and design cycle rather than the more costly production and test stage.

Another innovation at Salmesbury is the flexible infrastructure concept. In a £2.5m investment the entire factory was fitted with a false floor that allows easy reconfiguration to meet changing demands. The floor decking fits on cast iron support pedestals installed on a 1m square matrix, providing an accurate datum for tooling. All the jigs, tools and workbenches are designed to fit on these pedestals, and all the jigs have service points integrated into their design. The services themselves – electrical power, air lines, and IT connections – are installed under the false floor.

Eurofighter has rewritten the rules of designing and building militaryaircraft. Lean production, innovative technology and interchangeability will be the benchmarks for future projects. And these new methods are alreadypaying dividends for BAE Systems: the enthusiasm of its US competitors on the Joint Strike Fighter project to have BAE on the team is due in no small measure to its lean production expertise.