Bearing service life based on subsurface initiated contact fatigue can be estimated using the operating loads and speeds. These estimates assume that ideal conditions exist i.e. the bearing has been mounted properly with adequate support, is properly lubricated, and there is no preexisting damage. A bearing may fail prematurely due to a variety of conditions including loading that is heavier than expected, inadequate lubrication, improper mounting (misalignment, unsuitable fits), contamination, surface damage from improper handling, and poor maintenance practices. Each of these adverse conditions will result in a unique type of damage to the bearing contacting surfaces. In most cases examination of the bearing and mating components will reveal indications of the underlying cause of the premature failure for which corrective action must be taken to improve bearing performance. Examples of bearing damage and the root cause of the damage is provided in the following sections.