The purpose of this paper is to present an overview of ultrasonic and radiographic techniques and principles in detecting internal flaws in engine components i.e. flywheel and piston. Numerous NDT techniques are available today for detecting flaws in a variety of materials, but only ultrasonic and radiographic can be applied effectively for the detection of internal flaws through the volume of large masses of material. Both have their own advantages and disadvantages, and each requires considerable adequate skill to use the method to its best advantage. Flaws that are usually encountered in ingots (engine components) are microporosity, inclusion, segregation, hot tear, airlock, sponginess and shrinkage cavity.