The maintenance & engineering model of ZFL, an approved instrument in the field of further development and improvement of helicopter components

Hans W. Weber Peter Richter ZF Luftfahrttechnik GmbH, Germany ZF Luftfahrttechnik (ZFL) has been engaged in maintenance, repair and overhaul of dynamic helicopter components for almost 40 years. Comprehensive support of these functions does not only include workshop activities, but also continuous development and improvement of these components. The basic concept was and still is to operate helicopters over their complete utilization cycle economically, with the correct technological standard and operational equipment and to ensure as well as improve the reliability in operation. This paper is intended to describe the variety of technical events resulting from the basic concept as well as the maintenance model developed by ZFL. By means of concrete examples it will be shown that it is possible to significantly improve DOCs, decrease spare parts requirements, increase TBO cycles and to improve reliability aspects by using a special policy, integration of design and development capabilities and logistical analysis models within the maintenance process. Among other things, it will be shown how it was possible to increase, for instance, TBO cycles by up to 300 % or 400%. Furthermore, it will be demonstrated that even by the development of complex repair procedures despite extensive qualification and acceptance activities the need of spare parts can be reduced. 1.0 Introduction There is hardly anything which does not have to be or cannot be improved. Helicopters are one of these things and in particular their dynamic components. As it often happens, however, aspects to be improved become evident only in the course of utilization and as we all know because helicopters stay much longer in use nowadays than originally intended. Partly obsolete and inefficient technologies are thus carried along for decades. The bitter consequence: operating costs, servicing and spare parts costs are not in line with the state of the art.