Rolling element bearings may experience fatigue failure after a length of service. What is the first evidence of the beginnings of fatigue failure?

Correct Answer: Option D — The presence of small cracks in the races.

Fatigue failure in rolling element bearings initiates as subsurface cracks in the load-carrying surfaces of the races. Under cyclic loading, these cracks propagate to the surface, eventually causing spalling or flaking. Early detection of these microscopic cracks is vital for predictive maintenance and preventing catastrophic failure of critical shipboard machinery.