Typical helicopter simulation programs rely on differential equations of a closed form. However, since these equations are derived using various assumptions, their usefulness is limited to small flight regions and specific model types. This paper presents a component based rotorcraft simulation program. The program adopts methods of multi-body dynamics and is written in an object-oriented programming language. The program was validated using an AH-1G helicopter simulation. The trim results are well matched with flight test data. It is also shown that program is capable of running in real-time on a desktop computer.