Turbine apparatus includes turbine wheels by which introduced motive fluid is expanded; a horizontally disposed turbine shaft which is rotatably supported by inlet-side and outlet-side bearings, such that the turbine wheels are fixedly connected to the turbine shaft between the inlet-side and outlet-side bearings; a turbine housing by which the turbine wheels and the outlet-side bearing are encased; and a bearing cartridge in which the inlet-side bearing is housed that is mounted externally to the turbine housing. The bearing cartridge is separable from the turbine housing to facilitate a maintenance operation when the inlet-side bearing is disengaged from the turbine shaft. In a method for accessing a malfunctioning inlet-side component contactable with the turbine shaft in order to perform a maintenance operation, the bearing cartridge is dismounted from a surface of the turbine housing and the bearing cartridge is axially displaced in a direction away from the turbine housing.