Abstract: A method for detecting air-contamination within a hydrodynamic bearing used with a disc drive comprises in one embodiment, a method to detect air-contamination with hydrodynamic fluid by measuring operating signals of the disc drive between different external air pressure conditions (including ambient) on the hydrodynamic bearing and comparing the operating signals to predetermined threshold values. In another aspect, the invention provides an air-contamination detecting apparatus adapted to detect air-contamination within the fluid of a hydrodynamic bearing. In another aspect, the invention provides a method to determine air-contamination within hydrodynamic bearings using the change in disc drive input/output signals responsive to air-pressure changes on the hydrodynamic bearings.