This paper presents an improvement of inspection maintenance actions to reduce common cause failures of k-out-of-n redundant structures. Improving maintenance tasks for the programmable logic controllers with 1002 voting configuration and the control valves with 2003 voting configuration in a thermal power plant is described as an illustrative case study. The proposed improvement is based on common-cause avoidance in replacement and repair procedures. Performances of the proposed technique are verified through reliability modeling of two interested voting configurations. The suggested maintenance improvement can increase the system reliability for redundancy as needed to maintain critical functions.