A disc drive includes a base plate and a structural cover removably attached to the base plate to form an internal environment within the disc drive that is filled with a low density gas such as helium. A sealing cover is permanently attached to the base plate and the structural cover to form a hermetic seal for the low density gas. A first seal secured between the base plate and the removable structural cover permits short term operation of the disc drive with minimal leakage of the low density gas so that the drive can be tested prior to permanent attachment of the sealing cover.