Mass production of wind turbines (on an industrial scale) is a relatively young industry (less than a decade old) and, as such, robust operational data is hard to come by. It is not uncommon for experts to rely on anecdotal data to manage predictive maintenance (what component is likely to fail, on which turbine, and how to avert it). Inadequate documentation, for example the lack of maintenance comments recorded on completed work orders, and inconsistent review of comments provided, is a systemic problem.