A bowed rotor is caused by what?

A bowed rotor is primarily caused by improper warmup or overheating of the rotor. When a rotor does not experience a proper warmup, it can lead to uneven expansion of the material due to temperature gradients, resulting in deformation or bowing. Overheating can exacerbate this situation, as excessive heat can alter the material properties and lead to warpage.

In contrast, while incorrect blade adjustment, centrifugal forces during operation, and overloading of the engine can affect performance and efficiency, they do not specifically lead to the characteristic deformation seen in a bowed rotor. Proper warmup is crucial in ensuring balanced thermal expansion, maintaining the rotor's structural integrity, and preventing bowing.