Multi-function surface testing facility installed by George Koch

The installation in Chester, UK is now understood to be one of the largest such facilities in the world and operates alongside a purpose-designed water treatment plant, also installed by George Koch. The multi-stage, self-contained installation is now a key element in the manufacture of Airbus wings and associated components.

“The move from chromic acid-based chemical solutions to tartaric sulphuric acid meant that the original visual inspection method for crack detection could no longer be utilised,” commented Steve Moseley, sales manager at George Koch. “The use of fluorescent penetrant dye inspection was considered the most appropriate alternative – the procedure being centred on the application of fluorescent penetrant spray and developer powder, followed by a detailed UV inspection.”

To create a focus for the facility and to accommodate space restrictions at the site, George Koch’s solution was to build a single self-contained PFD inspection chamber. This would not only house the 11 separate stages that form part of the process, but would also enable ambient light to be shut out to create the ideal environment for UV inspection at the end of the line. Operations within the enclosure include spray, rinse and drying before the application of the developing powder to aid visibility during the manual UV inspection.

A innovative handling system is central to the design of the new system. Based on a floor-mounted gantry which moves laterally through the enclosure, station by station, relevant process nozzles and applications are presented to each component as it proceeds. “The final stage sees the UV lighting for the penetrant dye being assessed by specialist operators – a procedure which is optimised by the enclosed configuration. “Any potential defects are revealed as fluorescent indications,” adds Steve Moseley.

He also draws further attention to a number of other key design features that have addressed particular performance objectives specified by Airbus. He continued: “The oven element of the PFD booth, for example, has been designed to fulfil a dual role because it raises the relevant air temperature to some 70°C and also performs the dry-off function as required. Additionally, the chamber features other elements that optimise the operation including a raised grid floor with a stainless steel under-floor, and insulated supply and return duct work to enable various air flow profiles and temperature settings to be achieved.” He points out that the control system can also be set to function in several different modes, enabling the PFD processes to be optimised for each operation.

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