This paper provides a comprehensive investigation of Unmanned Aerial Vehicles (UAVs), focusing on an in-depth analysis of their avionics systems. The review explores the purpose-classified electronics hardware within UAVs, analyzing their performance metrics and the algorithms used for data processing, flight control, surveillance, navigation, protection, and communication. It highlights the importance of understanding UAV design processes, particularly in electric smart grid applications. The paper also discusses the challenges and failures associated with UAVs, including mechanical and software issues, as well as environmental factors affecting their performance. It emphasizes the need for a detailed analysis of UAV subsystems to improve design and maintenance. The review covers five main subsystems: control, computing, communication, sensory, and power. Each subsystem is analyzed in terms of its functions, integration, and performance. The paper also discusses various navigation strategies, including vision-based and AI-based techniques, as well as path planning and obstacle avoidance methods. Additionally, it examines target tracking and payload integration, highlighting the importance of accurate and efficient control systems. The review concludes with a discussion on the future of UAV technology and its potential applications in various fields. The paper aims to provide an informative background on UAV design processes and contribute to the knowledge base of UAVs.This paper provides a comprehensive investigation of Unmanned Aerial Vehicles (UAVs), focusing on an in-depth analysis of their avionics systems. The review explores the purpose-classified electronics hardware within UAVs, analyzing their performance metrics and the algorithms used for data processing, flight control, surveillance, navigation, protection, and communication. It highlights the importance of understanding UAV design processes, particularly in electric smart grid applications. The paper also discusses the challenges and failures associated with UAVs, including mechanical and software issues, as well as environmental factors affecting their performance. It emphasizes the need for a detailed analysis of UAV subsystems to improve design and maintenance. The review covers five main subsystems: control, computing, communication, sensory, and power. Each subsystem is analyzed in terms of its functions, integration, and performance. The paper also discusses various navigation strategies, including vision-based and AI-based techniques, as well as path planning and obstacle avoidance methods. Additionally, it examines target tracking and payload integration, highlighting the importance of accurate and efficient control systems. The review concludes with a discussion on the future of UAV technology and its potential applications in various fields. The paper aims to provide an informative background on UAV design processes and contribute to the knowledge base of UAVs.