Durability testing of engine mounted components is often performed using sine testing. To ensure that all resonance frequencies are excited, swept sine is used across the frequency range of excitation for the engine. This can be very costly and time consuming. A consortium of German automobile manufacturers recently approved the use of multiple simultaneous swept sine tones to reduce the time and cost of durability testing of engine mounted components. This paper describes a new multi frequency sine control technique that uses multiple swept sine control loops with independent digital tracking filters. The primary advantage of this technique is that it significantly reduces the required test duration. The result is a system capable of smooth continuous sine sweeps that excite all frequencies in the test range without sacrificing control performance.