Once a compressor is broken in, which of the following factors will most likely cause blade tips to rub?

Correct Answer: Option D — Failure of a rotor bearing

Rotor bearing failure allows the compressor shaft to deviate from its design centerline. This radial displacement causes the rotor to shift, leading to uneven clearances between blade tips and the stator casing. Consequently, the blades strike the casing, resulting in severe tip rub and potential catastrophic engine damage.