Within the Aircraft MRO (Maintenance, Repair and Overhaul) business KLM Royal Dutch Airlines Engineering & Maintenance Division has been involved with Thermal Spraying since the late 60’s. The latest procurement on thermal spraying is the state of the art light weight electric arc spray gun (the EM-14) for the closed-loop electric arc spray system of Praxair TAFA called the CoArc. With this new piece of equipment KLM is up-to-date in the high-tech approach of applying thermal spray coatings on aircraft engines with a electrical twin-wire arc spray system. Close teamwork between an end-user in aircraft industry (KLM) and a thermal spray supplier (Praxair) resulted in a new state of the art arc spray gun. This paper shows the first spray results with the EM-14 gun.

KLM Royal Dutch Airlines has the oldest Maintenance, Repair and Overhaul (MRO) shop for aircraft in the world (more than 80 years old). The company’s philosophy in all areas, including thermal spray, has always been to pursue the latest innovations and to maintain well-equipped facilities with state-of-the-art processes, equipment and materials for performing repairs. In the area of thermal spray, the latest procurement is a state-of-the-art unique cabinet with a high enthalpy plasma spray process. This new cabinet and new plasma spray process provides up-to-date technology for applying thermal spray coatings on aircraft engines. In this paper, experiences and the latest results obtained using this system to deposit various types of coatings used on aircraft will be reported.

The goal of this work is to have standardized quality control of thermal spray coatings incorporated into the Standard Practices Manuals of all aircraft engine original equipment manufacturer’s around the world. With the many manufacturers’ criteria for evaluation of thermal spray materials, laboratories are forced to have multiple criteria/systems to test and analyze coatings. As airlines/repair shops are moving towards overhaul of more variable engine types/models in their shops, the need to have a common evaluation system has been identified and is currently being addressed. A sub-committee of the European Airline Committee for Materials Technology is currently working to formulate this common system for thermal spray coatings evaluation. Participants are from GEAE, Pratt & Whitney, Rolls Royce, SNECMA and KLM Royal Dutch Airlines. The progress and goals of this group will be documented and reported.

This paper discusses the ongoing development of a standard for manufacturing and testing thermal spray coatings used in the repair of aircraft engines. Excellent progress has been made in eliminating non-value added tests and in defining a system for preparing metallographic specimens and conducting microstructural evaluations. Paper includes a German-language abstract.