Eurocopter chooses RADView Putting a new spin on safety

Safety and reliability are crucial in all aspects of the aerospace industry, but nowhere more so than in helicopter manufacture, especially when it comes to the structural integrity of the rotor blades. Whereas most fixed-wing aircraft have multiple engines and moreover derive lift from their forward momentum, the safety of a helicopter literally hangs from its rotor blades. Eurocopter now uses GE Inspection Technologies' RADView Computed Radiography System for examination of these vital parts.

The Eurocopter group was formed in 1992 by the merger between the helicopter divisions of Aerospatiale-Matra (France) and DaimlerChrysler Aerospace (Germany). The group is now a fully-owned subsidiary of EADS (European Aeronautic, Defence and Space Company), one of the three largest aerospace groups in the world.

The Eurocopter product range covers both civilian and military helicopters. The company has four main plants, two in Germany (Danauworth and Ottobrun) and two in France (Marignane and La Courneuve). The plant in La Courneuve produces the rotor blades and employs over 750 people. To give an idea of the production capacity of the plant,

La Courneuve turns out one main rotor blade and one tail rotor blade every hour. While rotor blades may at first sight seem simple in structural terms, in actual fact a great deal of high technology goes into them. After all, the rotors are what keep the helicopter in the air! In the past, rotor blades were made of metal, but since 1968 composite materials have been used, with spools of fibreglass thread forming the starting point. Composites have many advantages over metal, including longer lifetime, repairability and the ability to assume complex shapes.

Hanging by a thread
While rotor blades may at first sight seem simple in structural terms, in actual fact a great deal of high technology goes into them. After all, the rotors are what keep the helicopter in the air! In the past, rotor blades were made of metal, but since 1968 composite materials have been used, with spools of fibreglass thread forming the starting point. Composites have many advantages over metal, including longer lifetime, repairability and the ability to assume complex shapes.

All the blades are subjected to non-destructive testing using various techniques such as conventional radiography, real-time imaging, ultrasound, eddy current, magnetoscopy, dye penetration and more recently computed radiography (CR). The choice of technique depends on the type of blade being examined and the kind of defect being looked for. GE Inspection Technologies's RADView CR system is used in particular for large-scale inspection.

The radiography inspectors at La Courneuve are certified COFREND COSAC levels 1 and 2, with two labs at their disposal. One uses conventional radiography to look for tiny defects in small testpieces, while the other uses the Digital system for larger objects.

All rotor blades are first examined all over with real-time imaging, which involves exposing nearly 100 X-ray films every day. However, the introduction of the Digital system should eventually make it possible to eliminate the use of silver-based film.

When safety meets convenience
Philippe Gaignard, head of Technical Quality and NDT at La Courneuve, explains the advantages of the Digital CR system. "Where previously we had to make 10 film exposures for a large blade, we now make just two exposures on the phosphor imaging plates, as it is possible to work with different grey levels on the same exposure, giving images with different optical densities.

This means considerable time savings for the company, in terms of processing, interpretation and archiving of the images. Not only are there fewer exposures, but interpretation can be done almost immediately. Previously it used to take 10 to 15 minutes to expose each silver halide film. Also, the image can be viewed by several technicians at once. It is then sent over the network for archiving on a data storage medium; we don't need a special storage area any more. There are also ecological advantages, since processing chemicals are no longer used. Finally, there are economic advantages, since the phosphor plates are reusable as long as they are treated with suitable care."

A high-tech company such as Eurocopter, where safety and quality are top priorities, naturally seeks the most advanced techniques and the best systems to guarantee these requirements.

With GE Inspection Technologies and its RADView CR system, Eurocopter has found a resolutely future-oriented partner.