The Unmanned Aerial Vehicles (UAVs) are part of our society. According to recent reports from retail research, sales of drones have been tripled over the last few years to about $200 million. The aim of the paper is to highlight the most relevant maintenance actions to take in order to properly maintain commercial UAVs. Describing the main components and characteristics of a UAV, the research wants to provide quick guidelines and suggestions for effectively maintaining micro UAVs. Based on a structure analysis and on the most common flying modes, firstly the paper simulates mechanical stresses on the UAV quadcopter body frames using Finite Element Methods (FEM). Secondly, it analyses the results highlighting the weak aspects of the structure in order to predict possible failure mechanisms and to create effective maintenance approach for guaranteeing high level of product reliability and availability. Finally, it discusses the results for ensuring constant mechanical properties and performance for the entire lifetime of the product.