Airbus A380: a challenge of mounting large scale

Jean-Luc Lagardère in Toulouse facilities are essential for the A380 because it is in them where are all the elements necessary to assemble the aircraft. Production of the latest Airbus model is divided into several units.

The 40 post of unit 1 is responsible for final assembly of the aircraft (wing/wing structure). To this end, reference is made to each element (structure of the wing/wings) with respect to others. This means respecting the geometry of the plane defined by the design department. The construction of the A380 project began in 1998 and raised many challenges: the huge dimensions of the structures of the wings, the ovoid shape of the aircraft (circular in other cases) or the fuselage with double bridge. The objective was to also delete the templates of reference that had been used until the A340 program. These templates should be very precise for the Assembly of the aircraft and it was also necessary to carry out a periodic verification, as it was the template itself which guaranteed the position of the wings in space structures.

Rather than take the template as a reference (which meant many problems regarding the accumulation of tolerances), it was decided to measure the aircraft directly, i.e. measuring elements with respect to the others, serving as a reference. Another objective was to get solutions for mounting to complex contact surfaces (ovoid, double bridge). The idea of mounting by means of measurements convinced the perpetrators of the A380 programme.

Thierry Fabre, in charge of the project of Assembly by means of measurements of Toulouse, explains: "the basis of this work is beyond the simple mounting: was it necessary that all European production plants would agree with the references of the aircraft;" but each had their own ways of working, its objectives and its own restrictions on editing. "Therefore, the preparatory phase was essential to ensure the consistency of the data from all Airbus plants."

Multiple projects with laser trackers from Leica Geosystems (RCT in Nantes, Erebus in Meaulte, put mounting 15/21 in St Nazaire, measurement of contact surface of the structures of the wing of the A320 in Toulouse) are already currently being developed.

Martial Charraud, who had already participated in the project of measurement in Nantes (RCT) and Toulouse (A320) and joined the team of Thierry Fabre for the A380, says that "the first projects of aircraft assembling Airbus through measurement were developed in close collaboration with the parent company of Leica Geosystems in Switzerland." Given the success of this initiative, when we had to select a provider for the Assembly of the A380, we obviously went to Leica Geosystems. The objective was to take advantage of our experience and apply it to the A380. "In addition, he was personally very familiar with Leica Geosystems products and my confidence in them was absolute."Production of the A380 is designed so that its useful life to reach the 30-40 years, which is why the choice of good partners, reliable and durable, is very important. The methods used will become obsolete very quickly, especially the automation and computerization programs. "For example, the guarantee of maintenance of the old material is essential." We rely on a long term relationship. "In addition, already fully have the assurance that during the gradual process of assembling all the tools will be operational" added Fabre.

After defining the tools and methods of configuration, it was necessary to study the lines of vision of lasers trackers in a very dense environment with CAD [computer-aided design] tools. In fact, within the set of platforms and metallic structures which form the mounting post, is difficult to ensure "lines of sight" between the plane and the laser tracker measurement points. "We had to fix the concept, to determine the number of lasers and its optimal position: a growing challenge", points out Charraud.

Initially selected four laser trackers from Leica: two for the fuselage and two for the wings. The four were interdependent and were linked by a common reference. This system guarantees the homogeneity and the possibility of exchanging the laser trackers. The development of the specific programme for measurement and steering is linked to the EmScon program. Leica Geosystems has provided support for the development of the script.

One of the difficulties of the project was to validate the entire measurement process before becoming the first aircraft. (Not had with the structures of the wings or the wings previously). It was therefore necessary to get an idea of the procedures for testing and validating test structures partially simulating the dimensions of the aircraft. Aircraft No. 1 (MSN O1) allowed to validate the entire process of measurement scale.