Within last a few years tactical, operational and strategic UAV usages have become very common. Some UAV's mission duration may last more than 24 hours with a range of more than 1500 km. That long duration and range makes structural health monitoring (SHM) of UAV's very crucial. However, is it really necessary to monitor the structural health of every UAV? Is there any limit when considering the mission and the scale? Is damage tolerance methodology applicable to large scale UAV's? Such issues will be investigated during the study.