Once the critical failure modes have been identified, a maintenance strategy can be selected based on logical RCM decision tree [7, 6, 9] and probabilistic models for maintenance optimisation [5]. RCM optimises the various maintenance strategies based on the findings from the functional failure analysis. For gearboxes, planning and implementing a PM programme under the RCM approach can be complicated due to the variety of gearbox designs installed in turbines under different operating conditions. A key focus area when implementing RCM is that inspection manuals and procedures should be designed and prepared by a technical team with both field and design experience. This on the one hand, will help the design engineers to ensure that the service technicians’ tasks are aligned to design guidelines so that after a series of maintenance tasks or inspections, the results will be easilydesigns are now seeing modifications which will allow such repairs especially for offshore applications [8]. This now calls for a more holistic view to the design of wind turbine gearboxes (and other components) where the serviceability and operation life is taken into account during the design. It can be argued that since the wind industry is still relatively young, it has had to learn from its experience in order to make such improvements in design. The authors emphasise that, the way forward would be for more close integration of the field O&M activities to upstream design through adequate feedback for redesign and improvements (this is discussed further in the next section). correlated to the design information. While on the other hand, those with field experience will ensure that the technical guidelines can be interpreted into a language the service technicians understand. Another key area where a good link between the O&M activities and design is needed is in assessing the design for maintainability of major systems. In the case of a wind turbine gearbox the question RCM points out in the design phase is how easy it is to
disassemble, gain access to major components and then assemble especially when repairs are to be done inside the turbine (up-tower). In current gearbox designs, the capability of up-tower repairs is limited not only due to the lack of competency or tools but due to the difficulty in accessing and disassembling major components. Future Gearbox