The purpose of two or more valve springs in aircraft engines is to:

The purpose of incorporating two or more valve springs in aircraft engines primarily revolves around eliminating valve spring surge. This phenomenon occurs when a single spring cannot effectively control the motion of the valve at high engine RPMs or under varying loads. By utilizing multiple springs, the system can manage the oscillations and vibrations that might lead to instability and poor valve operation.

Using more than one spring can help maintain consistent and reliable valve closure and opening, even at higher speeds, reducing the risk of valve float. Valve float can significantly impair engine performance and lead to potential engine damage. Thus, having multiple valve springs ensures that the valves operate smoothly and efficiently, which is crucial for maintaining optimal engine performance and reliability in aircraft applications.