This course provides a comprehensive foundation in direct current (DC) electrical theory and its applications in aircraft systems. It introduces fundamental electrical quantities such as voltage, current, resistance, and power, and develops analytical skills through the application of Ohms Law and Kirchhoffs Laws in series, parallel, and combined circuits. Students explore energy sources including batteries and DC generators, examining their construction, operation, and performance characteristics within aviation systems. The course integrates practical elements through circuit assembly, measurement using multimeters, and systematic troubleshooting of faults, enabling students to interpret circuit behavior and apply safe maintenance practices in accordance with EASA Part- 66 Module 3 requirements.