The use of autonomous unmanned aerial vehicles (UAVs) for small scale maintenance tasks such as blasting, painting and ultrasonic thickness (UT) measurement of industrial infrastructure surfaces is considered. A number of modest but new improvements such as sensing using a 3D non-linear Lidar, unique navigation implementation, filtering using a predictive sliding window filter with mutating window size, coverage planning using custom parametric function and pseudo-velocity control are made which lead to an appreciable increase in performance of the integrated system. This allows the UAV to achieve higher levels of operating capability than currently reported. These improvements are reported in detail. Real world experiments are conducted which demonstrate the feasibility of endowing autonomy to UAVs for successfully executing small maintenance tasks when coating thickness requirements are in the order of hundreds of microns. Social impacts include improving worker safety conditions when performing inspection and maintenance at heights by eliminating scaffolding construction and reducing manual effort.